Question

A paper is in the form of a rectangle PQRS in which PQ = 30 cm and QR = 21 cm A semicircular portion is cut off from it as
shown in figure Find the area of ​​the remaining portion

Answer 1

area of reactangle = l×b
= 30×21
$610 {cm}^{2}$
area of semicircle=
$(1 \div 2 )\times pi \times {r}^{2}$
$(1 \div 2) \times( 22 \div 7) \times (21 \div 2)(21 \div 2)$
(11×3×21)/4
693/4
$173.25 {cm}^{2}$
required area =area of rectangle - area of semicirlce
=610-173.25
$436.75 {cm}^{2}$

Answer 2

area of rectangle = area of paper
area of paper = l×b
area of paper = 30×21
=630
area of semicircle=pi r^2÷2
r= 21÷ 2
r= 10.5
= 22/7×10.5×10.5
=346.5÷2
=173.25
remaining area= area of paper - area of semicircle
=630 -173.25
= 456.75