The perimeter of a rectangle is 60 cm. Its length is twice its width. Find its length.
The perimeter of a rectangle is 60 cm. Its length is twice its width. Find its length.
w = width
l = length
p = perimeter
\(\begin{array}{|rcll|} \hline p=60 &=& 2(w+l) \quad | \quad l = 2w \\ 60 &=& 2(w+2w) \quad | \quad : 2 \\ 30 &=& w+2w \\ 30 &=& 3w \quad | \quad : 3 \\ 10 &=& w \\ \mathbf{w} &=& \mathbf{10} \\\\ l &=& 2w \quad | \quad w=10 \\ l &=& 2*10 \\ \mathbf{l} &=& \mathbf{20} \\ \hline \end{array}\)
The length is 20