Question

The radius of the circle whose circumference is 5 times of the circle circumference of the circle with diameter 18 cm

Answer 1

2 pi r=5×2×pi×9

2r=10×9

r=45

Answer 2

The radius of the circle whose circumference is 5 times the circumference of the circle whose diameter is 18 cm is 45 cm.

• Let the radius of the circle be r.
• Given,

Diameter of second circle = 18 cm

Radius of second circle = 18/2 = 9 cm

Circumference of circle = 5(2π(9))

2πr = 90π

r = 45 cm

• Therefore, the radius of the required circle is 45 cm.