1. Angle and Triangle Flash Cards
You need 15 index cards for this!

2. Angle A B C

3. Two rays with a common endpoint called a vertex
Two rays with a common endpoint called a vertex. Always name an angle with the vertex in the middle.

4. Adjacent Angles

5. Angles that share a vertex and a side.

6. Congruent Angles
64°
64° X Y

7. Angles with the same measure.

8. Vertical Angles

9. Angles formed by intersecting lines and are opposite each other
Angles formed by intersecting lines and are opposite each other. Vertical angles are always congruent!

10. Acute Angles

11. The measure of the angle is less than 90°.

12. Obtuse Angles

13. The measure of the angle is greater than 90° and less than 180°.

14. Right Angles

15. The measure of the angle is 90°.

16. Complementary Angles

17. The sum of the two angles is 90°.

18. Supplementary Angles

19. The sum of the two angles is 180°.

20. SCALENE TRIANGLE

21. All three sides have different lengths:

22. ISOSCELES TRIANGLE

23. Has at least 2 congruent sides

24. EQUILATERAL TRIANGLE

25. All three sides are congruent

26. ACUTE TRIANGLE

27. All of the angles are acute
(less than 90°)

28. OBTUSE TRIANGLE

29. One obtuse angle
(greater than 90 less than 180)

30. RIGHT TRIANGLE

31. Has one right angle (90°)

32. Parallel Lines

33. Lines that are the same distance apart and never intersect (same slope)

34. Perpendicular Lines

35. Lines that intersect forming a perfect right angle

36. Transversal

37. A line that cuts across two or more other lines

38. Corresponding Angles

39. Angles that are in the same position

40. Interior Angles

41. Alternate Interior Angles are “across” from each other on the “inside”:
(A and D) (B and C)

42. Exterior Angles

43. An angle that occurs outside of two lines when they are crossed by a transversal
Alternate Exterior Angles are “across” from each other on the “outside”:
(A and H) (B and G)