Choose a shape and enter every length in the same unit.
Starting values are an example. Replace them with your own.
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Enter your details and run the calculation.
Informational calculations. Check assumptions, dates and jurisdiction before making a decision.
Full disclaimerThe calculator gives the area and perimeter of the chosen shape. A circle's area is πr² and its circumference 2πr, so a circle with radius 5 has an area of about 78.54 and a perimeter of about 31.42. A triangle's area comes from Heron's formula using three sides, a rectangle's from a · b and a trapezoid's from (a + b) · h / 2, without a perimeter, because that also needs the leg lengths. Enter every length in the same unit.
The area of a circle equals π times the radius squared, A = πr². A circle with radius 5 has an area of about 78.54 square units and a circumference 2πr of about 31.42 units. If you know the diameter, divide it by 2 first.
Use Heron's formula: the semiperimeter is s = (a + b + c) / 2 and the area is the square root of s(s − a)(s − b)(s − c). For sides 3, 4 and 5 the semiperimeter is 6 and the area is 6. The calculator first checks that the sides can form a triangle.
METHOD
Rectangle ab; circle πr²; triangle by Heron’s formula; trapezoid (a+b)h/2.
TRACEABLE
Basic arithmetic or geometry using the formula shown. Uses only your inputs.
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