Find the angles of an isosceles triangle if one of them is 126 degrees

Since in an isosceles triangle the angles at the base are equal, and the sum of all the angles of the triangle is 180º, the angles at the base will always be acute. Based on this, we know that the angle of 126º is the angle ∠B opposite to the base.

In this way:

∠А = ∠С = (180º – ∠В) / 2;

∠А = ∠С = (180º – 126º) / 2 = 54º / 2 = 27º.

Answer: angles ∠А and ∠С are equal to 27º, angle ∠В is equal to 126º.