Question

the perimeter of a rectangle is 42cm and its area is 20sq.cm.find length and
breadth​

Answer 1

Answer:

let breath=X

then length=2x

perimeterof rectangle=2(l+b)

42=2(2x+x)

42=2(3x)

42=6x

42/6=x

7=X

then length=2x=2×7=14cm

breath=X=7cm

Answer 2

Answer:

length=20cm then breadth =1cm ; length=1cm then breadth= 20cm

Step-by-step explanation:

perimeter =2(l+b)=42

l+b=42/2=21   →→→→eq. 1

l×b=20

b=20/l    →→→→→eq. 2

putting value of b in eq. 1 we get

l+20÷l=21

l²+20-21l=0

l²-20l-1l+20=0

l(l-20)-1(l-20)=0

(l-1)(l-20)=0

hence l=1  orl=20

if l=1cm then b=20cm and if l=20cm then b= 1cm