# Find angle B in triangle ABC if angle C = 90 degrees, angle A – angle B = 20 degrees.

January 12, 2021 | education

| The sum of all angles in any triangle is 180 °. It is known that the angle С is equal to 90 °, so the sum of the other angles is equal to:

A + B = 180 ° – 90 ° = 90 °.

It is known that the angle B is 20 ° less than the angle A, we express it in terms of x and solve the problem using the equation:

х ° – angle В;

Then:

(x + 20 °) – angle A.

Let’s compose and solve the equation:

x + (x + 20) = 90;

x + x + 20 = 90;

2x + 20 = 90;

2x = 90 – 20;

2x = 70;

x = 70/2;

x = 35 ° – angle B;

(x + 20) = 35 + 20 = 55 ° – angle A.

Answer: 35 °

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