Find angle A if angle A is 5/6 of angle B and angle C = 70 degrees.

1. It is known that the sum of the angles of a triangle is 180 *.

2. By the condition of the problem, the angle С is equal to 70 *, which means

angle A + angle B = 180 * – 70 * = 110 *.

3. Let’s designate the angle В as х and compose and solve the equation.

angle B + angle A = x + 5/6 * x = 110 *;

(6 + 5): 6 x = 11/6 x = 110 *;

x = 110 * * 6: 11 = 60 *.

4. Find angle A.

Angle A = 5/6 Angle B = 60 * * 5: 6 = 50 *.

Answer: Angle A is 50 *.