In a rectangular trapezoid, the obtuse angle is 3 times the acute angle. Find the corners of the trapezoid.

Given:
ABCE – rectangular trapezoid,
angle C = 3 * angle E.
Find the degree measures of the angles of a rectangular trapezoid ABCE: angle A, angle B, angle C, angle E -?
Decision:
Consider a rectangular trapezoid ABCE. She has an angle A = angle B = 90 degrees, since the trapezoid is rectangular.
Let the degree measure of the angle E be equal to x degrees, then the degree measure of the angle C is equal to 3 * x degrees. We know that the sum of the degree measures of a trapezoid is 360 degrees. Let’s make the equation:
90 + 90 + 3 * x + x = 360;
180 + 3 * x + x = 360;
3 * x + x = 360 – 180;
3 * x + x = 180;
x * (3 + 1) = 180;
x * 4 = 180;
x = 180: 4;
x = 45 degrees – the degree measure of the angle E;
45 * 3 = 135 degrees – the degree measure of the angle C.
Answer: 90 degrees; 90 degrees; 135 degrees; 45 degrees.