Follow a worked example.
Every example below can be loaded using its calculator’s Reset example button. Inputs use centimetres, square centimetres or cubic centimetres as labelled, while angles use degrees.
Two bases and height
Given: Base a = 10; Base b = 6; Height h = 4.
A = (a+b)h/2
| Measurement | Calculated value |
|---|---|
| Area | 32 cm² |
| Midline | 8 cm |
| Height | 4 cm |
Two bases and two legs
Given: Base a = 10; Base b = 4; Leg c = 5; Leg d = 5.
Δ = |a−b|; x = (c²−d²+Δ²)/(2Δ); h = √(c²−x²)
| Measurement | Calculated value |
|---|---|
| Area | 28 cm² |
| Midline | 7 cm |
| Height | 4 cm |
| Perimeter | 24 cm |
Isosceles trapezoid
Given: Base a = 10; Base b = 6; Equal leg c = 5.
h = √[c²−(a−b)²/4]
| Measurement | Calculated value |
|---|---|
| Area | 36.660606 cm² |
| Midline | 8 cm |
| Height | 4.5825757 cm |
| Perimeter | 26 cm |
Area to height
Given: Area A = 32; Base b = 10; Other base c = 6.
h = 2A/(b+c)
| Measurement | Calculated value |
|---|---|
| Area | 32 cm² |
| Midline | 8 cm |
| Height | 4 cm |
Check the answer’s dimensions
An area contains a product of two lengths, while volume contains three. A perimeter or radius is still a length. If your input measurements are mixed between metres and centimetres, convert them to a common unit first. A realistic-looking number can still be wrong if the units were inconsistent.