Last updated: Jul 21, 2024

Isosceles Trapezoid Area Calculator

Q: How do I compute the area of an isosceles trapezoid given diagonal?

You can compute the area of an isosceles trapezoid as: A = 0.5 × d² × sin(φ) where: A is the area of the trapezoid; d is the length of a diagonal; and φ is the angle between the diagonals.

Created by Anna Szczepanek, PhD

Anna Szczepanek

PhD, Jagiellonian University in Kraków, Poland

Website

Holds a Ph.D. degree in mathematics obtained at Jagiellonian University. An active researcher in the field of quantum information and a lecturer with 8+ years of teaching experience. Passionate about everything connected with maths in particular and science in general. Fond of coding, she has a keen eye for detail and perfectionistic leanings. A bookworm, an avid language learner, and a sluggish hiker. She is hopelessly addicted to coffee & chocolate – the darker and bitterer, the better. See full profile

Check our editorial policy

Reviewed by Davide Borchia

Davide Borchia

Physicist by education, scientist by vocation. He holds a master’s degree in complex systems physics with a specialization in quantum technologies. If he is not reading something, he is outdoors trying to enjoy every bit of nature around him. He uses his memory as an advantage, and everything you will read from him contains at least one “I read about this five years ago” moment! See full profile

Check our editorial policy

New

Table of contents

What is the area of an isosceles trapezoid?Useful trapezoid resources FAQs

This isosceles trapezoid area calculator will help you deal with these very particular trapezoids. Recall that we say that a trapezoid is isosceles if its legs have the same length. You'll experience no trouble using Omni's isosceles trapezoid area calculator, but we know that life is hard, and you sometimes have to calculate with pen and paper. Don't worry — we will teach you how to find the area of an isosceles trapezoid with the help of dedicated formulas.

What is the area of an isosceles trapezoid?

There are several dedicated isosceles trapezoid area formulas:

bases a ,b and height h given: A = (a + b) × h / 2
bases a, b and leg c given: compute h via the Pythagorean Theorem (h is the square root of c² − (a − b)²/4) and A = (a + b) × h / 2
bases a,b and angle α given: compute h as tan(α) × (a − b)² / 4 and then A = (a + b) × h / 2
base a, leg c and angle α given: compute h as c × sin(α) and b as a − 2 × c × cos(α), then A = (a + b) × h / 2

Choose the isosceles trapezoid area formula that suits the available data (for notation, see the picture below). Or just use our isosceles trapezoid area calculator!