The base angles of an isosceles triangle are equal
The base angles are 15 degrees, while the vertex angle is 150 degrees
The base angles are given as:
Base = (6a- 3) and (a + 12)
So, we have:
Collect like terms
Divide both sides by 5
Substitute 3 for a in Base = (6a- 3),
So, the base angle is 15 degrees.
The vertex angle is calculated using:
So, we have:
Hence, the vertex angle is 150 degrees
Read more about isosceles triangles at: