Answer:
D
Step-by-step explanation:
The vertex of the triangle is adjacent to 90° on a straight line, so
vertex = 180° - 90° = 90°
The triangle has 2 congruent sides and is therefore isosceles with 2 congruent base angles, then
x = [tex]\frac{180-90}{2}[/tex] = [tex]\frac{90}{2}[/tex] = 45° → D
