# The width of a rectangle is fixed at 28 cm. What lengths will make the perimeter greater than 72 cm?

##### 1 Answer

Oct 16, 2015

#### Explanation:

Start by writing down the formula for the perimeter of a rectangle

#"perimeter" = P = 2 xx (l + w)" "# , where

In your case, you know that the width of the rectangle is set at *greater than* *exactly*

#P = 2 xx (l + 28) = 72#

#l + 28 = 72/2#

#l = 36 - 28 = "8 cm"#

This means that **for any length** that exceeds *greater* than

#2 x (l + 28) > 72#

#l + 28 > 36#

#l > "8 cm"#

**SIDE NOTE** *Don't be confused by the fact that the length turned out to be "shorter" than the width, that happens in some cases.*