Answer: ∠B = 50°
∠BCD = 40°
<u>Step-by-step explanation:</u>
ACB is a right triangle where ∠A = 40° and ∠C = 90°.
Use the Triangle Sum Theorem for ΔABC to find ∠B:
∠A + ∠B + ∠C = 180°
40° + ∠B + 90° = 180°
∠B + 130° = 180°
∠B = 50°
BCD is a right triangle where ∠B = 50° and ∠D = 90°.
Use the Triangle Sum Theorem for ΔBCD to find ∠C:
∠B + ∠C + ∠D = 180°
50° + ∠C + 90° = 180°
∠C + 140° = 180°
∠C = 40°
