Definition of Isosceles Trapezoid
A trapezoid in which non-parallel sides and base angles are equal is called as an Isosceles Trapezoid.
More About Isosceles Trapezoid
The diagonals of an isosceles trapezoid are equal.
Area of isosceles trapezoid is given by , where s1 and s2 are the lengths of the parallel sides and h is the distance (height) between the parallel sides.
Example of Isosceles Trapezoid
The given figure shows the sides AC and BD as equal. Also the base angles ∠C and ∠D, ∠A and ∠B are equal. So, it is an isosceles trapezoid.
Video Examples: Trapezoids : How to Solve an Isosceles Trapezoid
Solved Example on Isosceles Trapezoid
Ques: Find the measures of angle A, B, and D in the isosceles trapezoid.
- A. A = 45o, B = 135o, D = 90o
- B. A = 135o, B = 135o, D = 45o
- C. A = 135o, B = 90o, D = 135o
- D. A = 135o, B = 135o, D = 90o
Correct Answer: B
- Step 1: ∠C = ∠D = 45o [ABCD is an isosceles trapezoid.]
- Step 2: As ∠C and ∠A are consecutive interior angles formed by parallel lines, they are supplementary. ∠A + ∠C = 180o [AB || CD, AC transversal.]
- Step 3: ∠A = 180 o- 45o = 135o [Solve for A.]
- Step 4: ∠B = ∠A = 135o [ABCD is an isosceles trapezoid.]