Question

triangle abc is an isosceles right triangle. what is the measure of one base angle? 30° 45° 60° 90°

Explanation:

Step1: Sum of triangle angles

A triangle's angles sum to $180^\circ$.

Step2: Right angle measure

Right triangle has one $90^\circ$ angle.

Step3: Base angles calculation

Isosceles base angles are equal: $\frac{180^\circ - 90^\circ}{2} = 45^\circ$.

Answer:

B. 45°