How to Calculate the Angle of an Isosceles Trapezoid
- 1). Multiply the known angle by 2. Multiplying this angle by two represents two congruent angles of the trapezoid. For example an angle of 70 degrees would produce a product of 140 degrees (70 x 2).
- 2). Subtract the product of the multiplied angles from 360. This will remove the known angles from the total sum of the quadrilateral, leaving only the product of both needed angles. For example, subtracting the sum of two 70-degree angles from 360 would leave 220 (360 - 140 = 220).
- 3). Divide the difference of the two known angles subtracted from 360 by 2. This will provide the two unknown angles. For example, a trapezoid with a known angle of 70 would leave 220, after being multiplied by 2 and then subtracted from 360. Then, 220 divided by two leaves 110 for the unknown angles (220 / 2).
- 4). Add all four angles together. If the result does not add up to be 360, you may need to check for errors in your process. For example, a trapezoid with two 70-degree angles and two 110-degree angles forms a perfect isosceles trapezoid (70 + 70 + 110 + 110 = 360).