Explicação passo a passo:
A rectangle has two pairs of equal sides. (See the image).
The length is [tex]L[/tex].
We know that the perimeter is [tex]P=42[/tex] m [tex]=4200[/tex] cm. So, we have
[tex]10+10+L+L=4200\\\\20+2L=4200\\\\2L=4200 - 20=4180\\\\L=\dfrac{4180}{2}\\\\L=2090[/tex] cm
Remember that [tex]1[/tex] m [tex]=100[/tex] cm. So, [tex]42[/tex] m [tex]=42\cdot 100=4200[/tex] cm.
