Circles Homework Chapter 9 Exercise 1 1. For each of these circles, say whether the dotted line is a radius or a diameter :- (d) 2. Use two letters to name the line which is a diameter in this circle. Name the radius in the figure. M O D T Exercise 2 1. Calculate the circumference of this circle with a diameter of 10 cm. (copy this working) => C =!D => C = 3 14 x 10 cm => C =? cm 10 cm 2. Calculate the circumference of the circle 20 cm with diameter 20 centimetres. 3. Calculate the circumference of this circle :- 12 cm 0 5 cm 4. Calculate the circumference of this circle with RADIUS 0 5 cm. this is Chapter Nine page 47
5. Find the circumference of this circle :- 25 mm 6. The radius of this Mr Sad face is 20 centimetres. Calculate the circumference of his face. 20 cm 7. This motorway sign has a diameter of 62 centimetres. 62 cm Calculate its circumference. 70 8. Bert buys a stick of licorice and bends it into the shape of a semi-circle. The diameter of the semi-circle is 25 centimetres. Calculate the length of the licorice stick. 25 cm 9. Terry plans to use wooden logs to make a border around the part of his garden he uses for bedding plants. 2 4 m This part of Terry s garden is in the shape of a quarter-circle with radius 2 4 metres. Calculate the TOTAL length along which he needs to lay the logs. 10. Shown is a circular model railway layout. The diameter of the circular track is 2 8 metres. 2 8 m Calculate the distance the train covers when it goes once around the track. How far will it have travelled if it goes round the track 100 times? this is Chapter Nine page 48
Exercise 3E 1. Calculate the circumference of this 2 coin : 28 mm 2. Shown is a corner shelf in the shape of a quarter circle. Calculate the length of the curved part. 3. Calculate the PERIMETER of each of these shapes :- 34 cm 14 cm 8 m 9 5 cm 9 5 cm 8 5 m 11 mm (d) 16 mm 6 cm 14 cm 4. The path in a Fantasy Garden consists of a series of semicircles. Start Path Finish 120 m Calculate the length of the path in metres. 5. The diameter of the wheel on the wheelbarrow is 40 cm. Calculate the circumference of the wheel in centimetres. To completely cross a lawn, the wheel on the barrow turns 25 times. Calculate the length of the lawn (in metres). this is Chapter Nine page 49
Exercise 4E 1. Find the diameter d, of the circle shown with circumference C = 80 centimetres. (Use d = C!) C = 80 cm 2. Find the diameter of each of these circular plates. C = 62 8 cm C = 95 cm 3. Calculate the RADIUS of each of these circles by first calculating the size of their diameters : C = 75 cm C = 6 5 m 4. The circumference of the glass of this magnifying glass is 26 centimetres. Calculate its diameter. 5. The circumference of this ashtray is 48 centimetres. calculate the size of its RADIUS. 6. The circle just fits into the square. The circumference of the circle is 18 84 cm. Calculate the diameter of the circle and use this to calculate the area of the square. this is Chapter Nine page 50
Exercise 5E 1. Calculate the area of this circle with radius 5 cm. 5 cm 2. For following circles, calculate their areas : 8 mm 3 8 m 3. For this circle : 12 cm Write down the size of its RADIUS. Use this to calculate its area (show working). 4. The DIAMETER of this No Left Turn sign is 47 1 cm. Calculate the radius and the area of the sign. 5. The radius of this gold medal is 2 1 cm. Calculate the area of the gold face. 6. This circle just fits into this square. What is the DIAMETER of the circle? (d) Calculate the area of the circle. Calculate the area of the big square. Now use your answers to and to calculate the shaded area in the figure. 12 cm this is Chapter Nine page 51
Exercise 6E 1. Shown is a circle with radius 6 cm. Find the area of the whole circle. Now halve your answer to obtain the area of the semi-circle. 6 cm 2. Calculate the area of this semi-circle with diameter 20 cm. (Imagine it was a whole circle to begin with). 20 cm 3. Calculate the area of this quarter-circle, by imagining a whole circle first. 8 cm 8 cm 24 cm 4. Calculate the area of the rectangle. 15 cm Write down the diameter of the semi-circle. (d) (e) Write down the radius of the semi-circle. Calculate the area of the semi-circle. Calculate the area of the whole shape. 5. This square metal plate has four identical holes drilled out from it. Calculate the area of the square. Calculate the area of each hole. Calculate the area of the metal remaining after the holes have been cut out. 40 cm 16 cm 40 cm this is Chapter Nine page 52