In ΔABC, AC = BC and ∠ABC = 50°, the side BC is produced to D so that BC = CD then the value of ∠BAD is:

Answer: Option C

In ΔABC
∠B = ∠A = 50°
∠ACD = 50° + 50°
∠ACD = 100°
∠ACD is the external angle or ΔABC
∠ACD + ∠CAD + ∠ADC = 180°
∠CAD = ∠ADC
∵ AC = CD
2∠CAD = 180 - 100
∠CAD = 40°
∠BAD = 50° + 40°
∠BAD = 90°