Question

A rectangular cardboard is 70 cm long and 50 cm wide a circular disc of diameter 42 cm is cut out of the area of remaining board​

Answer 1

Solution :

Given that, the rectangular cardboard's

  • length = 70 cm

  • width = 50 cm

So, its area (A)

  = 70 * 50 cm²

  = 3500 cm²

Diameter of the circircular disc = 42 cm

So, it's radius be r = 42 / 2 cm = 21 cm

Thus, the area of the disc (B)

  = πr² cm²

  = π * 21² cm²

  = (22 / 7) * 21 * 21 cm²

  = (22 * 21 * 3) cm²

  = 1386 cm²

If the circular disc be cut out, then the area of the remaining portion be

  = (Area of the rectangular cardboard) - (Area of the circular disc)

  = (A - B) cm²

  = (3500 - 1386) cm²

  = 2114 cm²

Answer 2

here is your answer

Given,

length= AB = 70cm

breadth=BC = 50cm

Diameter of circle = 42cm

Hence,

radius of circle= OA = 42/2=21cm

refer to the attachment for diagram

Remember =>>>

Area of rectangle = length × breadth

Area of circles = πr^2

Now, According to question=>>

Area of remaining board

= area of recatangular board -

area of circular disk

= (70 × 50) - {π(21^2)}

= 3500 - (441)π

= 3500 - {(441 × 22)/7}

=3500 - 1386

=2114 cm^2

Hence the remaining cardboard area is 2114 cm^2.

Hope it helps

BE BRAINLY//