Question

Which of the following appears to be a right isosceles triangle?

Answer 1

Isosceles triangle= 2 concurrent sides
Right angle= 90°

So which one has two concurrent sides and a right angle? A. The right angle is marked as well as the sides.

C has 2 concurrent sides, but it's not marked as a right angle. Option B has neither of these.

Answer 2

A) there is a right angle where the little square is, meaning it is a right angle. The two tallies indicate that those two sides are equal. An isosceles triangle would have two equal sides.