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How to Calculate Plane Geometry

What is Plane Geometry?

Plane geometry (2D geometry) calculates properties of flat shapes: area, perimeter, and angles of circles, triangles, rectangles, parallelograms, and other polygons.

Formula

Circle: A = πr²; C = 2πr
A
bh; P = 2(a+b) — bh; P = 2(a+b)
C
2πr — 2πr

Step-by-Step Guide

  1. 1Circle: A = πr²; C = 2πr
  2. 2Triangle: A = ½bh; Perimeter = a + b + c
  3. 3Rectangle: A = lw; P = 2(l+w)
  4. 4Parallelogram: A = bh; P = 2(a+b)

Worked Examples

Input
Triangle: base 8m, height 5m
Result
Area = ½ × 8 × 5 = 20 m²

Frequently Asked Questions

What is Plane Geometry?

Plane geometry (2D geometry) calculates properties of flat shapes: area, perimeter, and angles of circles, triangles, rectangles, parallelograms, and other polygons. Use this calculator for accurate, instant results.

How accurate is the Plane Geometry calculator?

The calculator uses the standard published formula for plane geometry. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

What units does the Plane Geometry calculator use?

Enter values in the units shown in each input field. The calculator displays results in standard units and shows the calculation steps.

What formula does the Plane Geometry calculator use?

The core formula is: Circle: A = πr²; C = 2πr. Each step in the calculation is shown so you can verify the result manually.

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