The height drawn from the vertex B of the diamond ABCD divides the AD side in half. Find the corners of the diamond.

Since the height of the rhombus divides the side in half, it is also the median of the triangle, and therefore the triangle ABD is equilateral and AB = BD = AD. In an equilateral triangle, all angles are 60, then the angle BAD = ABD = BDA = 60.

Since the diagonals of the rhombus divide the angle at the apex in half, the angle ABC = 2 * ABD = 2 * 60 = 120.

In a rhombus, the opposite angles are equal, therefore, the angle BAD = BCD = 60, the angle ADC = ABC = 120.

AB = P / 4 = 20/4 = 5 cm.

ВD = 5 cm.

Answer: The angles of the rhombus are 600 and 1200.