Why? The triangle in the problem is an isosceles triangle. That means the two legs of the triangle are equal and the angle opposite to the equal legs are also equal. Therefore, angle C is also 74°. The sum of the interior angles of a triangle is equal to 180°. Thus, 180° = ∡A + ∡B + ∡C 180° = 74° + ∡B + 74° 180° = 148° + ∡B ∡B = 180° - 148° ∡B = 32°
