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Problem 173

Geometry Difficulty 1.2 Multiple choice CEMC Gauss (Grade 7) · Canada · 2016

The measures of two angles of a triangle are 25∘25^{\circ} and 70∘70^{\circ}. The measure of the third angle is

Pick one

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Official solution

The measure of the three angles in any triangle add to 180∘180^{\circ}.

Since two of the angles measure 25∘25^{\circ} and 70∘70^{\circ}, then the third angle in the triangle measures 180∘−25∘−70∘=85∘180^{\circ}-25^{\circ}-70^{\circ}=85^{\circ}.

The measure of the third angle in the triangle is 85∘85^{\circ}.

Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty, ordering) added by this project.