Question

Help isosceles & equilateral

Answer 1

a = 100°

Explanation:

This is an isosceles triangle, so angle b = angle c:

140° is an angle outside the triangle. We need the angle in the triangle:

180 - 140 = 40°

angle b = 40°

Total sum of angles in a triangle: 180°

180° = a + b + c

Find a:

= a + 40° + 40°

a = 180° - 80°

a = 100°

Answer 2

100°

Explanation:

a + b = 140° because the sum of two interior angles in a triangle is equal to an exterior angle

Since this triangle is isosceles, which means QP = QR we can find the value of b as 40° because its supplementary to 140° that means the value of a = 140 - 40 = 100°