Answer:
a = 62
Step-by-step explanation:
The sum of the angles of a triangle is 180 degrees
a + 47+71 = 180
Combine like terms
a +118 = 180
Subtract 118 from each side
a+118-118=180-118
a =62
3 x 6 = 18
3+ 6 - 9
no. of vertices = no. of isosceles triangle