Answer:
2(X) + a° =180°, X = a°/2 +90°
Explanation:
In an isosceles triangle the sides XY & YZ are equal, as well as the angles oppose to those sides:
∠ X = ∠ Z and ∠ Y = a° (given)
We know that ∠X + ∠ Z + ∠ Y =180°, Since ∠ X = ∠ Z, then:
2(X) + a° =180°, X = a°/2 +90°