Geometry Vocab

1. The angles opposite each other when two lines cross. They are always congruent.
6. A part of a line that has a fixed starting point (endpoint), and then continues toward infinity.
8. a statement that can be demonstrated to be true by using definitions, postulates, properties, and previously proven ideas.
12. A quadrilateral in which all sides are congruent.
13. A type of triangle that has three congruent sides.
14. Two supplementary angles that share a vertex and a side.
17. a regular pattern made up of flat shapes repeated and joined together without any gaps or overlaps.
18. A statement that includes the phrase "if" and "then".
19. Two angles whose measures add up to exactly 180 degrees.
20. A type of triangle that has at least two equal sides.
22. A type of transformation that preserves the size and shape of the pre-image.
23. A perpendicular segment from a vertex to the line containing the base.
25. Two non-overlapping angles with a common vertex and one common side
26. Two lines that have opposite, reciprocal slopes.
27. A line segment in a triangle that extends from any vertex to the midpoint of the opposite side.

2. Two angles whose measures add up to 90 degrees.
3. Parts that match between two congruent figures.
4. Circles with a common center.
5. Two figures that have the same size and same shape.
6. A type of polygon that has all equal sides and equal angles.
7. A quadrilateral in which the opposite sides are parallel.
9. A line that passes through two lines in the same plane at two distinct points.
10. The part of a circle enclosed by two radii of a circle and their intercepted arc.
11. To draw a circle that passes through all of the vertices of a polygon. The circle is called the circumcircle.
15. the same distance from each other or in relation to other things.
16. A statement that includes the phrase "if and only if".
19. A triangle that has three unequal sides.
21. A criteria that proves triangle congruent involving two pairs of sides and a pair of included angles.
24. A quadrilateral with exactly one pair of parallel opposite sides.