Question

The circumference of a circle is 4 cm more than thrice its diameter. What is the diameter of the circle? (Assume π = 22/7 )

Answer 1

Answer:

We know that;

Circumference of circle = 2πr = πd

Let the diameter be x cm.

4 + 3x = π * x

⇒ 4 + 3x = 22/7 * x

⇒ 7 ( 4 + 3x ) = 22x

⇒ 28 + 21x = 22x

⇒ 28 = 22x - 21x

⇒ 28 = x

∴ x = 28

Hence, the diameter is 28 cm.

Answer 2

Let the circumference of circle be C and diameter be D.

The circumference of a circle is 4 cm more than thrice its diameter..

C = 3D + 4

2πR = 3D + 4

2πR = 3(2R) + 4

2πR = 6R + 4

(44/7)R = 6R + 4

(44/7)R - 6R = 4

[(44 - 42)/7]R = 4

[2/7]R = 4

R = 4×(7/2)

R = 14cm

Diameter is twice the radius so,

D = 2R

D = 2× 14cm

D = 28cm