Proof problems
Answers are for parents and teachers.
1
What is the angle (in degrees) between the bisectors of adjacent angles?
90
2
Prove that each angle of an equilateral triangle is 60°.
All angles are equal, their sum is 180°, so 180° : 3 = 60°.
3
If two angles of a triangle are equal, what can be said about the opposite sides?
They are equal too.
4
The exterior angle is 130°, one non-adjacent angle is 50°. How many degrees is the other?
80
5
Make up one simple proof problem and write it in “Given, Proof” form.
Write a reason for each step.