Answer:
The measure of a base angle is 45°
Step-by-step explanation:
[tex]\triangle ABC[/tex] is an isosceles right triangle. That means, the measure of its vertex angle is 90°
As, the sum of all three angles in any triangle is always 180°, so the sum of two base angles will be: [tex]180\°-90\°=90\°[/tex]
Now, the triangle is an isosceles triangle, that means the measures of two base angles are equal to each other.
So, the measure of each base angle [tex]=\frac{90\°}{2}= 45\°[/tex]