Question

Find the radius of a circle whose circumference is equal to the sum of the circumferences of two circles of radii 15 cm and 18 cm​

Answer 1

Answer:

circumference=2πr

circumference=(2×22/7×15)+(2×22/7×18)

circumference=44/7×15=44×15/7=660/7

circumference=660/7(of 1 rst circle)

circumference=660/7+44/7×18

circumference=660/7+792/7

circumference=1452/7

1452/7=2×22/7×r

1452/7=44/7r

1452/7÷44/7=r

1452/7×7/44=r

363/11=r

33 =r

ANS:radius:33 cm

Answer 2

$\frac{20739}{100}$Answer:

The radius of the mentioned circle is 32.993 or 33cm.

Step-by-step explanation:

Given in the question,

• Radius of circle 1 = 15 cm,
• Radius of circle 2 = 18 cm,
• Circumference of the circle = Sum of circumferences of circles 1 and 2

Circumference of circle = $2\pi r$

1. Circumference of circle 1 = 2 x 22/7 x 15cm = 94.25 cm
2. Circumference of circle 1 = 2 x 22/7 x 18cm = 113.14 cm

Sum of the circumferences = 94.25 cm + 113.14 cm = 207.39 cm

Circumference of the circle = Sum of circumferences of circles 1 and 2

Circumference of the circle = 207.39 cm

Last step -

Radius of the circle = Circumference / $2\pi$

Radius =  207.39 x 7 / 2 x 22

Radius = 32.99 cm or aprrox 33 cm