Pythagorean theorem
Find a missing side in a right triangle. Choose whether the missing side is the longest hypotenuse or one of the two perpendicular legs.
MAKE THE FORMULA CLEAR
Common shape areas
Calculate triangle, rectangle or circle area from the dimensions for that shape. Keep all lengths in the same unit.
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Area
6square units
Area uses squared length units. Use radius for a circle and perpendicular height for a triangle.
Worked steps
- Triangle area = base × perpendicular height ÷ 2
Use the same unit for every length. The result is in that unit squared. A triangle's height is perpendicular to its base, not its sloping side.
Method and scope
Triangle area is base times perpendicular height divided by two. Rectangle area is length times width, and circle area is pi times radius squared.
For a circle, the first dimension is radius rather than diameter and a second dimension is unnecessary. Area has the square of the chosen length unit.
Triangle height is perpendicular to its base, not the sloping side. The tool assumes ideal geometry and does not account for holes, overlaps or construction tolerances.
What this helps you do
Calculate triangle, rectangle or circle area from the dimensions for that shape. Keep all lengths in the same unit.
What to enter
Start with shape, then fill the other relevant fields in the units shown. The field hints explain the required format and examples.
How the calculation works
Triangle area is base times perpendicular height divided by two. Rectangle area is length times width, and circle area is pi times radius squared.
Worked example
A triangle with base 8 and perpendicular height 5 has area 20 square units. A circle with radius 3 has area about 28.2743 square units.
Understanding the answer
For a circle, the first dimension is radius rather than diameter and a second dimension is unnecessary. Area has the square of the chosen length unit.
Scope and limitations
Triangle height is perpendicular to its base, not the sloping side. The tool assumes ideal geometry and does not account for holes, overlaps or construction tolerances.