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Perimeter and Area Calculator
Work out the perimeter and area of any shape — square, circle, triangle and more.
Examples (Rectangle)
How to use it
- Choose a shape from the six options at the top of the calculator.
- Enter the required measurements in the fields (all measurements must be positive).
- The result — perimeter and area — updates automatically with every change.
- Look at the formula shown with the values substituted in — great for understanding and for homework.
- For a triangle, the calculator checks that the triangle inequality holds.
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✍️ Written by the MathsUK teamChecked against the National Curriculum and GCSE specifications