Question

Length of a rectangular feild is four times it's breadth.its area is 400 sq m . Find the perimeter.

Answer 1

$\huge \mathbb \red{ANSWER}$

$\large \bf \green { \underline{given \star} \: length(l) \: =4 \times breath(b) \: and \: aera(a) = 400sq.m} \: \: \\ \\ \large \bf \green{ \underline{to \: find \star \: perimeter(p)}} \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \:$

$\bf \purple{let \: length \: be \: x \: then \: breath \: = 4x} \\ \\ \bf \blue{ \boxed{aera \: of \: square = length \times breath}} \\ \bf \blue{400 = x \times 4x} \\ \bf \blue{400 = 4x {}^{2} } \\ \bf \blue{100 = x {}^{2} } \\ \bf \blue{x = 10m}$

$\bf \bf \color{darkblue}{ \red{ \star}then \: length = 10m \: and \: breath = 4x10 = 40m \: \red\star}$

$\bf \pink{ \boxed{perimeter \: of \: rectangle = 2(length + breath)}}$

$\bf \pink{perimeter \: = 2(10 + 40)} \\ \bf \pink{perimeter \: of \: rectangle = 2 \times 50} \\ \bf \color{darkblue}perimeter \: of \: rectangle = 100m$