About the parallelogram calculator
A parallelogram has two pairs of parallel sides. Its area is base × height, where the height is measured perpendicular to the base, not along the slanted side. Knowing two sides and the angle between them fixes the shape; so does a base, a height and one diagonal, which the calculator also handles.
Formulas
| Area | K = a·h = ab·sin θ |
| Perimeter | P = 2(a + b) |
| Diagonals | p, q = √(a² + b² ± 2ab·cos θ) |
| Diagonal identity | p² + q² = 2(a² + b²) |
Frequently asked questions
How do I find the area of a parallelogram?
Multiply the base by the perpendicular height: K = a·h. If you know the sides and angle instead, K = ab·sin θ.
How long are the diagonals?
p = √(a² + b² + 2ab·cos θ) and q = √(a² + b² − 2ab·cos θ). Their squares always sum to 2(a² + b²).