Question

Triangle TIC is an isosceles triangle with a vertex angle I. If the measure of Angle I = 90degrees, then find the measure of angle T.
A. 15degrees

B. 45degrees

C. 90degrees

D. 30degrees

Answer 1

It's B.  An isosceles triangle has two angles that are the same because they are across from 2 sides that are the same.  Therefore, these 2 angles must have the same measure.  Because of the triangle angle-sum theorem, all the angles add up to 180.  So 180-90 = 90 and 90/2 = 45