# Find the angles of an isosceles trapezoid if one of its angles is 70 °

September 14, 2021 | education

| Given:

ABCE – isosceles trapezoid,

angle A = 70 degrees.

Find the degree measures of the angles of the trapezoid ABCE: angle B, angle C, angle E -?

Solution:

Consider an isosceles trapezoid ABCE. Its angles at the base are equal to each other, that is, angle A = angle E = 70 degrees, angle B = angle C.

We know that the sum of the degree measures of a trapezoid is 360 degrees. Then:

angle A + angle B + angle C + angle E = 360;

70 + angle B + angle B + 70 = 360;

2 * angle B = 360 – 70;

2 * angle B = 290;

angle B = 290: 2;

angle B = 145 degrees.

Answer: 145 degrees; 145 degrees; 70 degrees.

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