Question

Plz help with number 1

Answer 1

In an isosceles triangle, the base angles are congruent. The third angle is called the vertex angle.

Here, the vertex angle is <A.

Therefore, m<C = m<B.

m<A = 3m<B + 20

m<A + m<B + m<C = 180

3m<B + 20 + m<B + m<B = 180

5m<B + 20 = 180

5m<B = 160

m<B = 32

m<C = m<B = 32

Answer: m<C = 32 deg