Geometry Review Flash Cards

Transcription

1 point is like a star in the night sky. However, unlike stars, geometric points have no size. Think of them as being so small that they take up zero amount of space. point may be represented by a dot on a piece of paper. point is usually named with a capital letter D Line: Through any two points there exists exactly one LINE. That is two points define a line. straight line extends forever in both directions. The name of a line passing through points suur and can be written as line or as. It may also be referred to as line. Endpoints: n endpoint is a point used to define a line segment or ray. D Rays: We may think of a ray as a straight line that begins at a certain point and extends forever in one direction. The point where the ray begins is known as its endpoint. The name of a ray with endpoint and uuur passing through point is ray or. The arrowhead denotes the direction the ray extends in; there is no arrow head over the endpoint.

2 Opposite Rays: Two rays with a common endpoint that form a straight line. uuur uuur and suur make ollinear Points: Points through which one line can be drawn. ollinear points lie on the same line. D Non-ollinear Points: Three or more points that do not lie on the same line. Plane: an be thought of as a flat surface extending infinitely in all directions. Through any non-collinear points there exists a plane. plane has no thickness. Planes are usually represented by a shape that looks like a tabletop or a parallelogram. plane is named by a single letter (plane m) or by three non-collinear points (plane ). m Intersecting lines: The term intersect is used when lines, rays, line segments or figures meet, that is, they share a common point (point of intersection). D

3 Perpendicular lines: Two lines that intersect to form right angles (angles that have a measure of 90 degrees). square at the point of intersection denotes a right angle. We write it with the symbol. We say line n is perpendicular to line m; we write it as line n line m. m n Parallel lines: Two lines in the same plane that never intersect (have no points in common) are called parallel lines. We write is with the symbol. We say line is parallel to line ; we write it as line line. n angle is formed by two rays with a common endpoint called the vertex of the angle. The rays are called the sides of the angle. Three letters can be used to name an angles such as. The middle letter will always denote the vertex of the angle. n angle can also be named with a number, for example or. Right angle: n angle whose degree measure is 90. cute angle: n angle whose degree measure is greater than 0 and less than 90.

4 Obtuse angle: n angle whose degree measure is greater than 90 and less than 80. Straight angle: n angle whose degree measure is 80. ongruent angles: ngles that have the same measure. PQR. linear pair of angles is a pair of adjacent angles who share a common ray and are supplementary. The opposite rays form a straight line. Supplementary angles are two angles whose measures combined equal 80 degrees. omplementary angles are two angles whose measures combined equal 90 degrees.

5 djacent angles: Two angles are adjacent if and only if they share a common side. m = m isector of an angle: ray that divides an angle into two congruent angles. m = m m = m Vertical angles: Whenever two lines intersect to form four angles, the non-adjacent angles are called vertical angles. If two lines intersect, then the vertical angles are congruent. transversal line intersects two other coplanar lines. We say that transversal line t intersects lines a and b. It forms two types of angles: Interior angles Exterior angles b a t

6 m = m 6 m = m 5 If two parallel lines are cut by a transversal, alternate interior angles are congruent. lternate interior angles are interior angles on the opposite sides of the transversal that do not have a common vertex m = m 8 m = m 7 If two parallel lines are cut by a transversal, alternate exterior angles are congruent. lternate exterior angles are exterior angles on the opposite sides of the transversal that do not have a common vertex If two parallel lines are cut by a transversal, corresponding angles are congruent. m = m 5 m = m 6 m = m 7 m = m 8 orresponding angles: one interior angle and one exterior angle that are on the same side of the transversal and do not have a common vertex