Math
posted by Millie .
Answer with Always, Sometimes or Never True. Kindly explain why so that I can understand. Thanks.
1. An interior angle and an exterior angle of a triangle are supplementary.
2. The bisector of an angle of an isosceles triangle is also a perpendicular bisector.
3. The sum of two side lengths of a triangle is less than the length of the third side.

#1 is always true. Draw a triangle. Extend one side so that you can see the interior and exterior angles. They add up to a straight line (the extended side). Thus they are supplementary.
#2 sometimes
#3 never
Have you tried drawing the triangles to illustrate the ideas?