The diagonal of the rectangle intersect at an angle of 20 °. Find the corners that form a diagonal

The diagonal of the rectangle intersect at an angle of 20 °. Find the corners that form a diagonal with the sides of the rectangle.

The diagonals of the rectangle intersect and form four isosceles triangles, which are equal in pairs. The angles at which the diagonals intersect are the apex angles of the isosceles triangles.
Consider a triangle with a 20 ° apex angle.
The angle at the base in this triangle or the angle between the diagonal and the side will be (180 ° – 20 °) / 2 = 80 °.
Consider the second isosceles triangle, the apex angle of which will be 180 ° – 20 ° = 160 °.
The angle at the base in this triangle is: (180 ° – 160 °) / 2 = 10 °.
Answer: the diagonal forms angles of 80 °, 10 ° with the sides of the rectangle.