Question

a rectangle has a perimeter of 72cm if its length is 20 cm then area of the rectangle in square centimere is

Answer 1

perimeter of the rectangle =2 (l+b)

let us assum the b as 'x'

72=2 (20+x)

72=40+2x

72-40=2x

32=2x

x=32/2

x=16

so the breadth is 16cm

area of rectangle =l×b

=20×16

=320cm square

Answer 2

Answer:

320 cm²

Step-by-step explanation:

Given =

Perimeter = 72 cm                                                                                 Length = 20 cm

Find =

Area of rectangle

Solution :-

Perimeter of rectangle = 2 (L+b)

          72 cm              = 2 (20+b)

         72 cm              = 40 + 2b

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

          72- 40 = 2b

              32    =  2b

            $\sf{\dfrac{32}{2} = b}$

           $\sf{16=b}$

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Area of rectangle = Length × Breadth

                             =  20 × 16

                             =  320 cm²