Answer:
β = 22.5°
Explanation:
In a triangle, the sum of interior angles must add up to 180°.
Since the angle marked with corners is equal to 90°, we can write an equation to solve for β.
3β + β + 90° = 180°
4β = 180° - 90°
4β = 90°
β = 90° / 4
β = 22.5°