Question 764258
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Remember that the sum of the 3 angles in any triangle is 180.

In an isosceles triangle, both the base angles are equal. 

Let the measure of the vertex angle be x.

Then the measure of each base angle = 4*x + 30.

Sum of the 3 angles = 2(4*x + 30) + x = 180

{{{8*x + 60 + x = 180}}}

{{{9*x = 120}}}

{{{x = 40/3}}}

Measure of each base angle = {{{4*40/3 + 30 = 160/3 + 30 = 250/3}}}


:)

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