In a triangle ABC, BC is produced to D so that CD = AC.

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In a triangle ABC, BC is produced to D so that CD = AC. If ∠BAD = 111° and ∠ACB = 80°, then the measure of ∠ABC is :

1. 31°
2. 33°
3. 35°
4. 29°

Correct Option: D

As per the given in question , we draw a figure of a triangle ABC in which BC is produced to D so that CD = AC

Given , ∠BAD = 111° and ∠ACB = 80°
∴ ∠ACD = 180° – 80° = 100°
∠CAD = ∠CDA [CD = AC]

∠CAD =	80°	= 40°
	2

∠BAC = 111° – 40° = 71°
∠ABC = 180° – 71° – 80° = 29°