Question

ABCD is a rectangle with AB - 42 cm and
BC=28 cm. Two quadrants with centres Dand
C are drawn. Find the shaded area.
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Answer 1

Answer:

Here we have a rectangle and Two quadrants

First quadrant is from d and second one is from c.

So now

Required area = area of rectangle - area of quadrants first and second

so

area of quadrant one will

$\pi \times r {}^{2} \div 4$

here radius is radius of one is equal= 28(as bc=ad)

so,

22/7×28×28/4

so we get

22×28

=616cm^2

Now area of quadrant second

$\pi \times r {}^{2} \div 4$

here we can find radius as we have

DC=42cm

as radius of first quadrant is 28

and DC=42

so radius of small quadrant= 42-28

=14cm

so area of second quadrant will

22/7×14×14/4

so we get

22×28/4

=154cm^2

Now

first quadrant + second quadrant=616+154=770cm^2

Now as we know area of rectangle= l×b

so it is 42×28=1176cm^2

Now required area = area of rectangle - area of first and second quadrant

= 1176-770

=406cm^2

Therefore

The shaded region = 406cm^2