Trapezoid Calculator
Find area, perimeter, midsegment, legs and angles from two parallel bases, height and horizontal offset.
Formula
S=(a+b)h/2; m=(a+b)/2; legs=√(d²+h²), √((a−b−d)²+h²).
Lower base a: 10 cm · Upper base b: 4 cm · Perpendicular height h: 4 cm · Area ≈ ((10 cm × 0.01 m/cm)+(4 cm × 0.01 m/cm))×(4 cm × 0.01 m/cm)÷2×10000 · Perimeter ≈ ((10 cm × 0.01 m/cm)+(4 cm × 0.01 m/cm)+(0.05)+(0.05))×100 · Midsegment ≈ ((10 cm × 0.01 m/cm)+(4 cm × 0.01 m/cm))÷2×100 · Left leg ≈ (0.05)×100 · Right leg ≈ (0.05)×100 · A: lower-left ≈ (pi÷2-atan((0.03)÷(4 cm × 0.01 m/cm)))×180÷pi · B: lower-right ≈ (pi÷2-atan((0.03)÷(4 cm × 0.01 m/cm)))×180÷pi · C: upper-right ≈ 180-(53.13010235) · D: upper-left ≈ 180-(53.13010235)
How to use
- Enter lower base a, upper base b and height h.
- Enter upper-left offset d from the lower-left corner, in cm.
- Read A, B, C, D: lower-left, lower-right, upper-right, upper-left.
Examples
- Bases 10 and 4 cm, height 4 cm, offset 3 cm give area 28 cm² and perimeter 24 cm.
Frequently asked questions
What does negative offset mean?
The upper-left corner lies to the left of the lower-left corner.
Can the bases be equal?
Yes. This inclusive definition includes parallelograms and rectangles.
What is the midsegment?
The segment joining the leg midpoints; its length is (a+b)/2.
Sources
Updated: