One of the angles at the base of an isosceles triangle is 26 degrees. Find the rest of the corners of the triangle.

Let ABC be an isosceles triangle, angle A = 26 degrees. Since, by condition, an isosceles triangle is given, the angles at its base are equal. Then angle A = angle C = 26 degrees. The triangle sum theorem says that the sum of all interior angles of any triangle is 180 degrees, so:
angle A + angle B + angle C = 180 degrees;
26 + angle B + 26 = 180;
angle B = 180 – 52;
angle B = 128 degrees.
Answer: angle B = 128 degrees, angle C = 26 degrees.