How to find if acute / obtuse triangles are congruent

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SSAT Upper Level Quantitative › How to find if acute / obtuse triangles are congruent

Questions 1 - 1

If the vertex angle of an isosceles triangle is 30 degrees, what is the value of the angle that is exterior to one of the base angles?

$105^{\circ}$

$30^{\circ}$

$75^{\circ}$

$150^{\circ}$

$15^{\circ}$

Explanation

First, you subtract one angle so . Because there are 2 base angles you divide that value by 2 to get 75 Degrees. The exterior angle and the base angle are supplementary angles so .

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