Answer this an exterior angle at the base of an isosceles triangle triangle measure 125degrees. what is the measure of the vertex angle? a) 135 degrees b) 90 degrees c) 45 degrees d) 60 degrees

Comment
When an exterior angle is given, its complement can the found with the following formula.

Exterior angle + the supplement interior angle  = 180
Because the exterior angle is given, we can find the base angles and later on the apex angle. 

Solution
125 + x = 180 Subtract 120
x = 180 - 125
x = 55

The other base angle = 55
A triangle has 180 degrees
55 + 55 + apex angle = 180
110 + apex angle = 180
apex angle = 180 - 110
apex angle = 70 <<<<< Answer.
I'm not getting any of those. This is not ASAP. If you've put in something wrong let me know.

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