Question

If the measure of ABC = 180o, and the length of AD and DC are equal, which is the measure of 13 years ago

Answer 1

Possible answers

A. 30o
B. 45o
C. 90o
D. 180o

Answer 2

I think i just answered this question, but here it is again:

This triangle is an isosceles triangle because the lengths AD and DC are equal,

This triangle is also a right triangle because when the longest side is the diameter and the other point of the triangle is on the circle, a right triangle will be created.

An isosceles right triangle has the side lengths 90-45-45, and the angle ACD in this problem would be 45 degrees.