Question

What is the value of x?
A. 20
B. 30
C. 45
D. 60
E. 90

Answer 1

The sum of all the angles in a triangle is equal to 180°

Since the given triangle is an isosceles ∆ therefore the angles opposite to the equal sides with also be the same.

now from the diagram: 90° + 2x° = 180°

Therefore x = 45

Answer 2

C.45, a triangle has a total of 180 degrees. Since we know that there is a right angle of 90 degrees, we know that the rest of the two angles must also add up to 90. And since the last two angles are the same angle, what two same numbers add up to 90? 45