Question

Find the radius and perimeter of a circle whose area is 77 cm^2

Answer 1

area of circle = 77 cm^2
=πr^2 = 77
= (22/7) x r^2 = 77
= r^2 = (77 x 7) / 22
= r^2 = 49/2
= r = 7/√2 cm

perimeter = 2πr = 2 x 22/7 x 7/√2
= 22√2 cm

Answer 2

Radius of the circle is 7/√2 and perimeter of the circle is 22√2 cm.

• The area of the circle is given as 77 cm².

• Now area of circle is πr².

πr² = 77

r = 7/√2 cm.

• Now perimeter of the circle is the same as circumference of the circle.

• Circumference of the circle = 2πr = 2×22/7×7/√2 = 22√2 cm.

• Perimeter of the circle is 22√2 cm.