The Perimeter of Noncircular Shapes Study Guide
Introduction to The Perimeter of Noncircular Shapes
With me everything turns into mathematics.
—Renè Descartes (1596–1650)
This lesson will describe ways that geometry is used for measuring, specifically perimeter. Perimeter has many uses in real life outside of your math classroom.
When you measure the distance around a noncircular shape, you are finding its perimeter.
Perimeter is an addition concept; it is a linear, one-dimensional measurement.
To find the perimeter of a noncircular shape, add up all of the lengths of the sides of the figure. Be sure to name the units.
The perimeter of a square, or any rhombus, is equal to 4s, where s is the length of a side. Because all four sides are equal, when you measure the distance around a square, you get s + s + s + s, or 4s.
In a rectangle, like all parallelograms, the opposite sides are parallel and congruent. The perimeter of a rectangle is 2l + 2w, where l equals the length and w equals the width. Always remember that the length is longer.
To find the perimeter of a triangle, you just add up the lengths of all three sides:
Find the perimeter of a square whose side is 5 cm.
You know that each side of a square is equal. So, if you know that one side of a square is 5 cm, then you know that each side of the square is 5 cm. To calculate the perimeter, add up the lengths of all four sides.
- 5 + 5 + 5 + 5 = 20
So, the perimeter of a square whose side measures 5 cm is 20 cm.
Be alert when you work with geometry problems to make sure that the units are consistent. If they are different, you must make a conversion before calculating perimeter or area.
Find practice problems and solutions at The Perimeter of Noncircular Shapes Practice Questions.
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