Question

In triangle ABC angle a measures twice angle b. If an exterior angle at C measures 126, find angle a

Answer 1

than C =180 - 126 =54 degree
so than 180=a+b+c
180=2b+b+54
126=3b
b=126/3 =42
b=42
a=2b=2*42=84
a=84
b=42
c=54