Adjacent angles formed by two intersecting lines. Sum of the measures of the three angles in a triangle. Sum of the four angles in a convex four-sided figure. Sum of the angles for any convex polygon. Sum of exterior angles for any convex polygon.
Isosceles triangles have equal base angles.
Isosceles trapezoids have equal base angles. The bisector of a chord passes through the center of the circle. Opposite angles are supplements. Formula to calculate the length of an arc on a circle. It is linked directly to each of the twenty Conjecture Pages.