Question

a piece of wire in the form of a rectangle of 8.9 cm long and 54 millimetre broad is reshaped and bent in the form of a circle find the radius of the circle in millimetre

Answer 1

GIVEN :

length of the rectangle = 8.9 cm

8.9 cm = 8.9 * 10 mm

8.9 cm = 89 mm

$\bold \: { \: length \: of \: a \: rectangle \: = 89 \: mm } \\ \\ \bold \: { \: breadth \: of \: a \: rectangle \: = \: 54 \: mm \: } \:$





LENGTH OF THE WIRE = PERIMETER OF THE RECTANGLE

perimeter :

2 ( 89 + 54 )

$\bold \: { \: 2(143) \: mm \: } \:$





after bending in circle :

THE LENGTH OF WIRE = CIRCUMFERENCE OF A CIRCLE

2 ( 143 ) mm = 2 * π * r

143 = π * r

143 = 22 / 7 * r

r = 143 * 7 / 22

r = 1001 / 22

$\bold \:{ \: r \: = 45.5 \: mm \: } \:$