We're given that 2 sides of the triangle are equal, but one of its angles, Q, is different from the other angles. Therefore, PQR is an isosceles triangle and the measures of
angles P and R are equal. (The two angles opposite from the two equal sides of an isosceles triangle are equal.)
Since the measure of angle P is 30° greater than twice the measure of angle Q:
P = 30+2Q = R
The interior angles of a triangle always add up to 180°:
P + Q + R = 180
(30+2Q) + Q + (30+2Q) = 180
5Q + 60 = 180
Q = 24
Solve for R:
30 + 2(Q) = 30 + 2(24) = 78
Attachment:
trianglePQR.png [ 19.02 KiB | Viewed 515 times ]