Question 692981: A base angle of an isosceles triangle measures 50 degrees. Find the number of degrees in the measures of the vertex angle.
Answer by RedemptiveMath(80)   (Show Source):
You can put this solution on YOUR website! The vertex angle of an isosceles triangle is the angle that is NOT a base angle. Isosceles triangles have two base angles, so the vertex angle is the third angle. The two base angles of an isosceles triangle equal, so in this case we have two angles that measure 50 degrees apiece. If a triangle has a total measure of 180 degrees inside its shape, then we just solve for the third side by setting an equation equal to 180 degrees:
50 + 50 + x = 180
100 + x = 180
x = 80 degrees.
So, the vertex angle, or the angle that is not a base angle, is equal to a measure of 80 degrees.
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