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Alternate Exterior Angles - Problem 2

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Teacher/Instructor Brian McCall
Brian McCall

Univ. of Wisconsin
J.D. Univ. of Wisconsin Law school

Brian was a geometry teacher through the Teach for America program and started the geometry program at his school

A more complex application of alternate exterior angles is this problem right here. We’ve got 62 degrees, we’ve got two parallel lines, a transversal and 2y and x. So let’s start by using our alternate exterior angles.

2y and 62 are on opposite sides of that transversal and they’re on the opposite and the open side of the parallel lines which means 62 degrees must equal 2y since they are congruent which means if I divide by 2, then y is going to be 31 degrees.

So we can write that in, y equals 31 and since 2 times y is 62, so I’m going to erase 2y and write 62 and x since these two are a linear pair, they must sum to 180 degrees which means x has to be 118 degrees. So we used our alternate exterior angles that must be congruent and then we used our linear pair conjecture.

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