Answer :

**To Find:**A

**Given:**AB = AC and ∠ ACD = 70°

**Diagram:**

Now, as AB = AC,

∠ABC = ∠ACB [Angles opposite to opposite sides are equal]........(1)

And,

∠ACB + ∠ACD = 180º [Sum of angles on a straight line = 180º]

∠ACB + 110º = 180º

∠ACB = 70º

Now, from equation 1,

∠ABC = 70º

we also know that,

∠A + ∠B + ∠C = 180º[Sum of angles of a triangle = 180º]

∠A + 70º + 70º = 180º

∠A = 180º - 140º

∠A = 40º

Rate this question :

How useful is this solution?

We strive to provide quality solutions. Please rate us to serve you better.

Related Videos

Champ Quiz | Mastering Triangles44 mins

RD Sharma | Important Proofs in Triangles28 mins

Congruency and Similarity28 mins

Triangles - Important Questions39 mins

NCERT | Triangle Inequalities47 mins

Quiz | Are You Master of Triangles?48 mins

R.D. Sharma | Triangles33 mins

Champ Quiz | Congruency of TrianglesFREE Class

Champ Quiz | Know About Triangles50 mins

Quiz on Triangles32 mins

Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Expertsview all courses

Dedicated counsellor for each student

24X7 Doubt Resolution

Daily Report Card

Detailed Performance Evaluation