# Triangle angles

In a triangle ABC the interior angle at the vertex C is twice as the internal angle at the point A. Outer angle at the point B measured 117 degrees. How big is the outer angle at the vertex A?

Result

a =  39 °

#### Solution:

a+b+c=180
c = 2a
180-b = 117

a+b+c = 180
2a-c = 0
b = 63

a = 39
b = 63
c = 78

Calculated by our linear equations calculator.

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#### To solve this example are needed these knowledge from mathematics:

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