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In a polygon, the sum of the measures of the exterior angles — one at each vertex — is 360^(∘).
130
We are given the following diagram.
We are asked to find the value of x. Notice that the x^(∘) angle is one of the exterior angles of the polygon in the diagram. To find the measure of the x^(∘) angle, we will first recall an important piece of information.
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Exterior Angles of a Polygon |
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In a polygon, the sum of the measures of the exterior angles — one at each vertex — is 360^(∘). |
The exterior angles of the triangle have measures of x^(∘), 150^(∘), and y^(∘). These measures add up to 360^(∘). x^(∘) + 150^(∘) + y^(∘) = 360^(∘) We can use this equation to find the value of x, but we need to find the value of y first. Notice that the y^(∘) angle and the 100^(∘) angle form a straight line.
Therefore, these angles are supplementary and the sum of their measures is 180^(∘). y^(∘) + 100^(∘) = 180^(∘) Now we can solve this equation for y. For simplicity, we will not write the degree symbol.
Finally, we will substitue 80 for y into the first equation and solve it for x.
We got that x=130.