How to Throw Away Marks in Maths GCSE One tragedy that only people who have marked eternal eamination papers such as GCSE will have any real idea about is the number of marks that candidates just throw away in eaminations. Given that each mark in a GCSE eamination could be worth many thousands of pounds over your working life, it is a crazy situation to be in. Imagine that you had to give an eaminer a fifty pound note every time you threw away a mark in your GCSE eam. I m sure you wouldn t be very happy about that, but in reality you could be losing a great deal more over the course of your working life. Marks are very often lost by: Not reading the questions properly. Not answering the question asked. Not showing your working. Trying to do too much in your head. Not knowing your tables and wasting time having to work them out. Not knowing simple formulae such as the area of a triangle. Not knowing the names of all the common 2-D and 3-D shapes. Not knowing the difference between a factor and a multiple. Not being able to round answers correctly. Not knowing the meaning of common mathematical terms such as perpendicular, obtuse, corresponding angles and quadratic. Not knowing the properties of shapes such as parallelograms. Not knowing the difference between 5 and 5. Not being able to carry out transformations properly. The list goes on and on Ecept for the very brightest and most thorough of students (in other words, the vast majority of everyone else) even a casual read through by an eaminer will reveal a large number of throw aways - marks that could easily have been gained if only the candidate had taken more care in preparing for the eam. Please, please, please, don t be one of those candidates. Purchase the answers to the modules for the nominal sum of just 20 and check all your answers thoroughly, so you don t make these common mistakes. You ve been studying maths for eleven years Make sure you get the grade you deserve!
Home Study Modules KS4 Higher Level Pythagoras and Trigonometry Please enjoy using these free questions. If you would like fully worked answers to the questions in all the GCSE modules (similar to the free Graphs module answers) you may purchase an immediate download for just 20 by following the instructions on the home page of our website: http://www.gcsemathematics4u.co.uk GCSEMathematics4U Mathematics4u www.gcsemathematics4u.co.uk
Revision Topics C What you will be practising: Concept Pythagoras Theorem given a diagram. Eamples Given two sides in a right angled triangle, find the third side. Includes when you need to find the hypotenuse and when you know the hypotenuse and need to find one of the other sides. 4 m z 3 m Pythagoras Theorem given no diagram and you need to draw one first. Pythagoras Theorem applied to 3-D situations. 1. A ship left a port and travelled 152 Km due east and then 193 Km due north. How far was it from its starting point? 2. Two points A and B, are drawn on a co-ordinate grid. A is (a, b) and B is (c, d). What is the distance between A and B? A 7.6 cm B 8.5 cm C D F 7.2 cm E G Find AG H Trigonometry finding the values of sines, cosines and tangents and combinations of these functions. Trigonometry finding an angle given the value of sine, cosine or tangent of the angle. Trigonometry solving triangles. Find: a) sin 141 o, b) 9 tan 37 o, c) (sin 37.5 o ) 2 + (cos 37.5 o ) 2 sin = 0.7382, find the value of. 8.7 cm 51 0 Find Page 2
Trigonometry more advanced problems. Trigonometry - given no diagram and you need to draw one first. Bearings Solving problems using trigonometry applied to bearings. Trigonometry and Pythagoras Theorem to more comple problems. θ is one angle in a right angled triangle. Cos θ = 12 / 13 and the hypotenuse is 65 cm long. What is the length of the other two sides? Michael is flying a kite on a string 26 metres long. The angle of elevation of the kite is 42 o. Michael s hand is 1.4 metres above the ground. How high is the kite above the ground? A ship sails from a port P on a bearing of 206 o for a distance of 56 Km to an island Q and then changes direction to a bearing of 143 o for a distance of 98 Km to another port R. How far is the ship now east of its starting point and how far is it south of its starting point? A point P and two flagpoles are in a straight line. P is positioned such that P and the tops of the flagpoles are also in a straight line. The flagpoles are 25 metres apart, the smaller is 18 metres high and the angle of elevation from P to the tops of the flagpoles is 27.5 o. P 27.5 o 18 m 25 m Find the height of the taller flagpole. Problems involving mied trigonometry and Pythagoras Theorem in 3-D The base ABCD of a right square based pyramid is laid horizontally on a table. The verte P is directly over the centre of the base. AB = 12 cm. AP = 22 cm. Find: a) The height of the pyramid. b) The angle PDB. c) The area of one of the sloping faces. Finding sines, cosines and tangents and their inverses over the range of 0 o to 360 o. Give the angles,, between 0 o and 360 o for each of the following: a) sin = 0.5693 b) sin = 0.4792 c) cos = 0.428 d) cos = 0.9283 Page 3
The sine rule and cosine rule. Find the length in the following triangles: 78 o 56.4 m 58 o 12 cm 54 o 14 cm Mied problems involving sine rule, cosine rule and Pythagoras Theorem in two and three dimensions. Finding the area of a triangle using ½ ab Sin C Page 4
Normally we do not give you any clues in the question section, but there is one point that is so important we want to include it here at the beginning of this section. It is this: When solving right angled triangles (that is, when you are trying to find angles or sides given some information about the triangle) you only have two sets of tools available Pythagoras Theorem and Trigonometry there is nothing else. If you have this type of question in the eamination, which you are almost certain to have, don t sit there scratching your head. Decide whether to use Pythagoras or Trigonometry and get on with the question. How do you decide? Easy! If the question does not involve angles you are not given angles and you are not asked to find angles given the three sides of a triangle it must be Pythagoras Theorem. If you are given angles to use or are asked to find an angle, you should use Trigonometry. Simple as that! Q In some more complicated eamples, you may be given angles that you don t need to use straight away (they are ready for a later part of the question) as well as the lengths of sides, but by the time you get to those you will, hopefully, have had plenty of practice and will be able to pick your way through the questions. 1. a) State Pythagoras Theorem. b) Which is the longest side in a right angled triangle? 2. Calculate the distance z in each of the following triangles. Round the answers to three significant figures where appropriate. a) b) c) 11.8 m 4 m z z 6 cm 12.9 m z 3 m 5 cm d) e) z f) z 13 m 8.5 mm 12 m 6.33 mm 8.7 cm 3.2 cm z Page 5
3. A ladder is 15 m long and leans against a wall. The foot of the ladder is 4 m from the bottom of the wall. How far up the wall does the ladder reach? If the ladder is moved so that its foot is only 3 m from the base, how much further up the wall will the ladder reach? 4. What is the length of a diagonal of a rectangle 16.2 Km by 5.7 Km? 5. A ship left a port and travelled 152 Km due east and then 193 Km due north. How far was it from its starting point? 6. A flagpole is 22 m high and is constrained from bending in high winds by cables each 31 m long fied into the ground. Each cable is stretched tight. How far is each cable fied into the ground from the foot of the flagpole? 7. Two points A and B, are drawn on a co-ordinate grid. A is ( 2, 5) and B is (7, 9). What is the distance between A and B? 8. The top of a chimney on one house is 9.3 metres above the ground. The top of a chimney on another house is 6.9 metres above the ground. The chimneys are 15.6 metres apart, measured horizontally. A bird flies directly from the top of the higher chimney pot to the lower. How far does it fly? 9. Two points A and B, are drawn on a co-ordinate grid. A is (a, b) and B is (c, d). What is the distance between A and B? 10. Two points A and B, are drawn on a co-ordinate grid. A is (, y) and B is ( + a 2 1, y + 2a). What is the distance between A and B? 11. Show that a triangle with sides 3 367, 3 456 and 4 825 units respectively is right angled. 12. Show that a triangle with sides of length 2pq, p 2 q 2 and p 2 + q 2 will always be a right angled triangle, provided p and q are positive numbers and p>q. 13. What is the height of the vertical line of symmetry of this isosceles triangle? 11 cm 11 cm 9 cm 14. What is the area of each of these isosceles triangles? 6.7 mm a) b) 8.4 m c) 4.3 mm 12 cm 12 cm 8.4 m 6.7 mm 10.2 m 15 cm Page 6
15. A ship sails from a port P to an island Q, 100 Km south, then on to another island R, 142 Km east of Q. From R it travels south again 110 Km to another island S and finally east a distance of 205 Km to its destination T. a) How far is it from P to R as the crow flies? b) How far is it from R to T as the crow flies? c) How far is it from P to T as the crow flies? 16. Calculate the length of the diagonal from A to G in this cuboid. A 7.6 cm B 8.5 cm C D F 7.2 cm E G H 17. A B 12 cm C The diagram shows a square based right pyramid. The length of the sides of the base is 8 cm and the length of the sloping edges is 12 cm. O M D 8 cm Calculate: E a) the distance OB b) the vertical height of the pyramid OA c) the distance AM, where M is the midpoint of BE d) the total surface area of the pyramid e) the volume of the pyramid. 18. X Y A line is drawn diagonally on a can from X to Z via Y, as shown in the diagram. (Z is directly below X.) Z The can has a diameter of 13 cm and a height of 15 cm. What is the length of the line XYZ? Page 7
19. Find the value of the following, correcting to three significant figures where appropriate: a) sin 57 o b) sin 0 o c) sin 90 o d) sin 69 o e) sin 137 o f) cos 26 o g) cos 90 o h) cos 0 o i) cos 48 o j) cos 141 o k) tan 35 o l) tan 45 o m) tan 12 o n) tan 30 o o) tan 127 o 20. Find the value of the following, correcting to three significant figures where appropriate: a) 16.8 sin 12 o b) 9 tan 37 o c) 56 d) 19.4 e) 45.6 sin 105 o cos 18 o sin 69 o f) 7 cos 88 o g) 45 h) cos 56.4 o i) 19.5 cos 72 o j) 89.56 tan 36.8 o sin 23.5 o cos 141 o 21. Find the value of sin 63 o divided by cos 63 o. Find the value of tan 63 o. 22. Find the value of (sin 37.5 o ) 2 + (cos 37.5 o ) 2. 23. Find the value of (sin 16.83 o ) 2 + (cos 16.83 o ) 2. 24. Find the value of (sin 256 o ) 2 + (cos 256 o ) 2. 25. Find the value of in each of the following, giving the answers correct to one decimal place: a) sin = 0.7382 b) cos = 0.5915 c) tan = 0.3347 d) sin / cos = 0.2142 26. For each of the following triangles, find the value of sin, cos and tan. Leave your answers in fraction form. 26 cm a) b) 5 cm 10 cm c) 3 cm 40 cm 41 cm 24 cm 9 cm 4 cm sin = sin = sin = cos = cos = cos = tan = tan = tan = Page 8
27. In each of the following triangles, find the length of the side. a) 5 cm b) c) 34 0 43 0 4 cm 51 0 5 cm 28. In each of the following triangles, find the length of the side. a) b) c) 8.7 cm 51 0 38.6 0 12.9 cm 7 cm 67.3 0 29. What are the values of the angles in a 3-4-5 triangle? 30. What are the values of the angles in a 5-12-13 triangle? 31. θ is one angle in a right angled triangle. If cos θ is 0.7352, what is the value of θ? 32. θ is one angle in a right angled triangle. Sin θ = 9 / 41 and the opposite side to θ is 27 m long. What is the length of the other two sides? 33. θ is one angle in a right angled triangle. Cos θ = 12 / 13 and the hypotenuse is 65 cm long. What is the length of the other two sides? 34. θ is one angle in a right angled triangle. Tan θ = 48 / 55 and the hypotenuse is 438 cm long. What is the length of the side adjacent to θ? 35. Using the triangle below, give an algebraic proof that the sine of an angle divided by its cosine is equal to the tangent of the angle. p r q θ 36. Using the same triangle as in question 35, show that the square of the sine of an angle plus the square of the cosine of the same angle is 1. Page 9
37. C a b B m T c n A Here is a neat proof of Pythagoras Theorem that shows the close relationship between this theorem and trigonometry. Answer the parts of the question carefully to complete the proof. a) In triangle ACT, cos A = Use the small letters and write the answer as a fraction. b) In triangle ABC, cos A = Use the small letters and write the answer as a fraction. c) Use your answers to parts a) and b) to complete the equation b 2 =. d) In triangle BCT, cos B = Use the small letters and write the answer as a fraction. e) In triangle ABC, cos B = Use the small letters and write the answer as a fraction. f) Use your answers to parts d) and e) to complete the equation a 2 =. g) Use your answers to parts c) and f) to complete the equation a 2 + b 2 =. h) Hence complete the proof of Pythagoras Theorem. 38. A tower is 43m high. Julia stands a certain distance from the tower and measures the angle of elevation from the ground to the top of the tower to be 18 o. How far is she from the tower? 39. Michael is flying a kite on a string 26 metres long. The angle of elevation of the kite is 42 o. Michael s hand is 1.4 metres above the ground. How high is the kite above the ground? 40. A rectangle ABCD has dimensions AB = 8 cm and BC = 14 cm. What is the angle ACB? 41. A cliff is 156 metres high. A boat is 720 metres from the base of the cliff. What is the angle of depression of the boat from the top of the cliff? 42. If Larry stands 65 m from a building and the angle of elevation to the top of the building from the ground is 47 o, how high is the building? Page 10
43. A section of straight road 1.5 Km long rises 75 metres over its length. What is the average angle that the road makes with the horizontal? 44. Which bearings are represented by the following compass directions: a) East b) West c) South d) North e) North East f) South West 45. A ship travels 135 Km on a bearing of 135 o. How far is it east of its starting point? 46. An aircraft flies 340 Km on a bearing of 285 o. How far is it west of its starting point and how far is it north of its starting point? 47. A mountain P is 45 Km east and 34 Km north of another mountain Q. What is the bearing of mountain Q from mountain P? What is the back bearing of mountain P from mountain Q? 48. The angle of elevation to the top of a mountain from the base camp of a mountaineering epedition is measured very accurately to be 3.582 o. The horizontal distance from the base camp to the mountain is 56.43 Km. How high is the mountain above the base camp? 49. A ship sails from a port P on a bearing of 206 o for a distance of 56 Km to an island Q and then changes direction to a bearing of 143 o for a distance of 98 Km to another port R. How far is the ship now east of its starting point and how far is it south of its starting point? Give each distance correct to the nearest 100 metres. 50. An aircraft flies 890 Km from an airport on a bearing of 340 o and then changes to a bearing of 203 o and flies another 760 Km. a) How far is the plane now west of the airport? b) Is the plane now north or south of the airport and by how much? c) What bearing must the plane now fly in order to return directly to the airport? d) How far is the return flight assuming a direct return? 51. Michelle measures the angle of elevation to the top of a tower from the ground to be 63 o. Peter stands 22 metres behind her and measures the angle of elevation to the top of the tower to be 35 o. a) How far is Michelle from the tower? b) How tall is the tower? 52. A point P and two flagpoles are in a straight line. P is positioned such that P and the tops of the flagpoles are also in a straight line. The flagpoles are 25 metres apart, the smaller is 18 metres high and the angle of elevation from P to the tops of the flagpoles is 27.5 o. Find the height of the taller flagpole. P 27.5 o 18 m 25 m Page 11
53. Find the distance d in the diagram. 23 m 42 o 39 o d 54. F Q 19 o R P 98 m S 55 m The diagram represents a rectangular playing field PQRS. FR is a floodlight gantry in one corner of the field. PS = 98 metres. RS = 55 metres. The angle of elevation of the floodlight from the point Q is 19 o. Find: a) The height of the floodlight gantry. b) The length of the diagonal PR. c) The angle of elevation of the floodlight F from point P. d) The distance FS. e) The angle of elevation of the floodlight from the point S. 55. The base ABCD of a right square based pyramid is laid horizontally on a table. The verte P is directly over the centre of the base. AB = 12 cm. AP = 22 cm. Find: a) The height of the pyramid. b) The angle PDB. c) The area of one of the sloping faces. Page 12
56. A O B C In the diagram, the radius of the circle is 9.83 metres, the angle ABC is 38.5 o. Find: a) The length of OB. b) The area of OABC. 57. Give the angles,, between 0 o and 360 o for each of the following: a) sin = 0.5693 b) sin = 0.4792 c) cos = 0.428 d) cos = 0.9283 e) tan = 6.723 f) tan = 0.2735 g) sin = 2.452 h) 1 / cos = 6.32 58. State the sine rule for a triangle ABC. 59. Find the length in the following triangles: a) b) 78 o 56.4 m 48.2 o 58 o 19 cm 38.6 o c) d) 22 o 126 o 27 m 89.4 mm 146 o 32.9 o Page 13
60. A triangle has vertices A, B and C. a) Complete this form of the cosine rule: a 2 = b) Complete this form of the cosine rule: Cos A = 61. Find the length in the following triangles: a) b) 54 o 12 cm 14 cm 10.9 m 9.3 m 29.5 o c) d) 25.8 o 183 mm 88 cm 198 mm 157 o 38 cm 62. Find the angle marked P in the following triangles: P a) b) 18 m Q P 9.365 Km 5.942 Km 12 m 19 m Q 6.883 Km R R Page 14
63. What happens when you try to use the cosine rule to find angle Q in this triangle? P 4.2 cm Q 3.8 cm 8.1 cm R Eplain your answer. 64. Eplain how, given a triangle with no right angles, you would know whether to use the sine rule or the cosine rule, then try the questions below. 65. Peter is standing some way from the base of a small hill. On top of the hill is a vertical tower. Peter measures the angle of elevation to the top of the tower to be 29 o and the angle to the bottom of the tower to be 18 o. The direct distance of Peter from the base of the tower is 134 metres. Draw a diagram, labelling Peter s position P, the base of the tower B and the top of the tower T. a) Find the angle TPB. b) Find the angle PTB. c) Find the height of the tower. 66. A plane flies on a bearing of 067 o for 75 Km and then on a bearing 112 o for a further 99 Km. Find the distance, as the crow flies, of the plane from its starting position. 67. A trapezium PQRS has <QPS = 107 o, PQ = 84.5 m, PS = 76.4 m and SR = 115.6 m. a) Find the length of the diagonal QS. b) Find angle QSP. c) Find angle QSR. d) Find the length of QR. e) Find the area of the trapezium. Page 15
68. A surveyor is measuring a triangular piece of land TUV. TU is 56 m and TV is 65 m. The angle UTV is 69 o. Calculate: a) The perimeter of the triangle TUV. b) The area of the triangle. 69. A triangle ABC has AB = 10 cm, BC = 6 cm and angle BAC = 31 o. Show that there are two possible values for angle C. Demonstrate this difference by sketching and labelling the two possible triangles. 70. STU is a right angled triangle with the right angle at T. P is a point somewhere on TU. Angle TPS = 37 o, angle TUS = 21 o and PU = 243 metres. Find the length of ST. 71. P 7.84 m 20.74 m U S The diagram shows a structure made from steel struts that is to be used as part of a new bridge construction. It is assembled from two rectangular frames, PSUR and RUTQ joined at right angles along the line RU. Additional struts PQ and ST are welded into position. R T The dimensions are shown on the diagram. 15.63 m Q Calculate the following: a) The length of PQ to 2 d.p. b) The distance PT to 2 d.p. c) The length QU to 2 d.p. d) <PQR e) <UQS 72. Three points X, Y and Z lie on a circle. The angle YXZ is 42 o, the angle XYZ is 57 o and the distance YZ is 300 mm. a) Calculate the length of XY. b) Hence, or otherwise, find the area of triangle XYZ. c) Find the radius of the circle. 73. A triangle XYZ has XY = 54 cm, YZ = 71 cm and <XYZ = 4α a) Find the area of the triangle in terms of sin 4α. b) What value of α gives the maimum area of the triangle? c) What is the maimum area of the triangle? d) There are two possible values of α that give an area of 1200 cm 2. What are these two possible values? Page 16