Formula for Area

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Introduction
This page contains the formula for area of a square, rectangle, circle, parallelogram, triangle and trapezoid (trapezium). Examples are given to show you how to use these formulas.
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Square

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Formula
square with the sides L
formula for the area of a square
The lesson on the area of a square will explain the basics needed to understand this formula. Here's the summary:

All the sides (edges) of a square have the same length. If each side has the length L, the formula for the area A will be:
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Example
Given a square where the length of each side (edge) is 5cm. Find the area of this square.
Using the formula for the area of a square

Rectangle

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rectangle with width w and length l
Formula
The lesson on the area of a rectangle will cover the basics needed to use this formula. Here's a short summary:

If a rectangle has the length l and the width w, we can find the area A, by multiplying its width and its length together. Hence, we have: 
formula for the area of a rectangle
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Example
Given a rectangle with the length of 4ft and the width of 3ft. Find its area.
Using the formula for the area of a rectangle

Circle

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a circle with the radius r
Formula
The lesson on the area of a circle will explain to you on how to use this formula. Here's a short summary:

For a circle with the radius r, its area A, will be: 
formula for the area of a circle

Where π is constant that is approximately equals to 3.14.
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Example
Given a circle with the radius 3cm. Find its area.
Using the formula for the area of a circle
Take π = 3.14.

Parallelogram

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Formula
a parallelogram with the base b and height h
The lesson on the area of a parallelogram will show you the basic ideas on using this formula. Here's a summary:

For a parallelogram with the base b and the height h, the area A, is given as:
formula for the area of a parallelogram

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Example
Given a parallelogram with the base 5in and the height 3in. Find the area of this parallelogram. 
Using the formula for the area of a parallelogram

Triangle

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triangle with the base b and height h
Formula
The lesson on the area of a triangle will explain to you on how to use this formula.

Consider a triangle  with the base b and height h, the area A, of this triangle is simply:

formula for the area of a triangle

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Example
Given a triangle with the base 4cm and the height 2cm. Find its area.
Using the area formula of a triangle

Trapezoid (Trapezium)

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a trapezoid with the heigh h, and parallel sides of a and b.
Formula
The lesson on the area of a trapezoid will explain the steps on using its formula for area. Here's the summary:

For a trapezoid with the height h and two parallel sides a and b, its area A, is given as: 
formula for the area of a trapezoid

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Example
Given a trapezoid with the height of 4in, and two parallel sides of 2in and 3in respectively. Calculate its area.
Using the formula for the area of a trapezoid
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