1. Central angle = intercepted arc
2. Inscribed angle = 1/2 intercepted arc
3. If two sides of a triangle are 3 and 7, the third side must be greater than 4 and less than 10.
4. The midsegment of a triangle connects the midponts of any two sides of a triangle.
5. The midsegment is parallel to the 3rd side.
6. The midsegment = 1/2 of the 3rd side.
7. The midsegment forms 2 triangles that are similar.
8. In an equilateral triangle, the median, altitude, angle bisector, and perp bisector are all the same segment.
9. Triangles contain 180 degrees. Quads contain 360 degrees. Pentagons contain 540 degrees. Hexagons contain 720 degrees. Circles contain 360 degrees.
10. Number of degrees in convex polygon is (n-2)180.
11. Number of degrees in exterior angles of convex polygon is 360.
11. Acute triangle---each angle is less than 90.
12. Supplementary angles add to 180. Complementary angles add to 90.
13. Triangles are congruent by SAS, SSS, ASA, AAS, HL, and LL.
14. Triangles are similar by SSS~, AA~, SAS~
15. Similar triangles means corresponding sides are proportional and corr angles are congruent.
16. Similar triangles have a scale factor.
17. Scale factor is side/side. Use corresponding sides.