Answer:
Since the triangle in the picture has two equal sides, we can conclude that this triangle is an isosceles triangle. Also in an isosceles triangle, the base angles are equal, and the sum of three angles in a triangle is always 180°, we have the equation:
39° . 2 + x° = 180°
=> x° = 180° - 39° . 2
=> x° = 180° - 78°
=> x° = 102°
