Question

a paper is in the form of a rectangle of dimension 21 CM by 15 cm is semicircle along its length is cut as shown what is the area of the remaining part​

Answer 1

Answer:

Area of remaining portion =

= 141.75 sq. cm

Step-by-step explanation:

Given,

FOR RECTANGULAR PAPER :

Length(l) = 21 cm

Breadth(b) = 15 cm

FOR SEMI - CIRCULAR PART :

Since, the semi-circle is cut along the length of the rectangular paper. Then,

Diameter (d) of semi-circle = Length(l) of the rectangular paper.

d = l = 21 cm

We know that,

Radius(r) = diameter/2 = d/2

= 21/2 cm

Now,

Area of remaining portion =

= Area of paper - Area of semi-circle

= (Area of rectangle) - (Area semicircle) ....(1)

Area of rectangle = l×b = 21×15

= 315 cm^2 ...(2)

Area of semi-circle = (πr^2) / 2 =

= { 22/7 × 21/2 × 21/2 } / 2

= 693 / 4 cm^2

= 173.25 cm^2 ...(3)

From eq.(1) , eq.(2) and eq.(3) , we get,

Area of remaining portion =

= 315 cm^2 - 173.25 cm^2

= 141.75 cm^2

Hence,

Area of remaining portion =

141.75 sq. cm

Answer 2

21x15=315 cm sq. is the area of rectangle

area of semicircle =

pi rxr/2=22/7×21/2×21/2×1/2=173.25cmsq.

therefore remaining area =315-173.25

=141.75cm sq.

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