Question

Can somebody help me please

Answer 1

It's an isosceles triangle so angles A and BCA are congruent.  

Angle BCA is the supplement of BCD, so 180-109 = 71.

Angle A is congruent to that, so A=71 degrees.

Let's see if we can get that in the format they want, kind of as a proof.

1.  ∠BCD=109° Reason: Given

2. AB ≅ BC      Reason: Given

3. ∠BCA = 71°  Reason: Linear pairs are supplementary

4. ΔABC is isosceles.   Reason: Definition of isosceles

5. ∠A ≅ ∠BCA   Reason: Isoceles triangle theorem

6. ∠A = 71°         Reason: Def congruent

Answer: 71 degrees