The diagonal of the rhombus forms an angle equal to 20 degrees from one of the sides. Find the corners of the rhombus.

The diagonal of the rhombus divides the angle in half. This means that if it forms an angle of 20 ° from one of the sides, then the greater angle from which this diagonal emerges is twice as large, i.e. 40 °. The opposite angle will also be 40 ° by the definition of a rhombus. The sum of all the angles of the rhombus is 360 °. The sum of the two angles found is 80 °. Then the sum of the other two angles, which are also located opposite each other, is 360-80 = 280 °. These two angles are also equal to each other, therefore they are 280 ÷ 2 = 140 °.
The answer is 40 °, 140 °, 40 °, 140 °.