Angle at the apex

In an isosceles triangle, the angle at the apex is 30° greater than the angle at the base. How big are the internal angles?

Correct answer:

A =  50
B =  50
C =  80

Step-by-step explanation:

A+B+C = 180
A=B
C = 30+A

A+B+C = 180
A-B = 0
A-C = -30

A = 50
B = 50
C = 80

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