Question

How can you prove a triangle is isosceles?

A. Use the distance formula to see if at least two sides are congruent.

B. Use the slope formula to see if any sides are perpendicular.

C. Use the distance formula to see if all three sides are congruent.

D. Use the slope formula to see if any sides are parallel.

Answer 1

An isosceles triangle always has two congruent sides and two congruent angles, so it's A. :)