Find the corners of a rectangular trapezoid if one of its corners is 20.

A trapezoid is a quadrilateral with only two opposite sides parallel. These two parallel sides are called bases. The other two sides are called sides. A rectangular trapezoid has two corners of straight lines, since they are formed by two parallel lines and a secant, one of the angles from the condition of the problem is 20 degrees, the sum of all angles of the trapezoid is 360 degrees. The fourth angle of the trapezoid is 360 – (90 + 90 + 20) = 360 – 200 = 160 degrees.
Answer: The angles of the trapezoid are equal: 90, 90, 20, 160 degrees.