ABC is a right-angled triangle in which ∠A = 90° and AB = AC. Find ∠B and ∠C.

Since AB = AC,
So, △ABC is Right-angled isosceles.
∠B = ∠C.. (angles opp. to equal sides are equal)
∠A + ∠B + ∠C = 180°.. (angle - sum property of a triangle)
Substituting ∠B = ∠C, ∠A = 90°
90° + 2∠B = 180°
2∠B = 180° − 90° = 90°
⇒ ∠B = 45°
So, ∠C = ∠B = 45°.