Question

the radii of two circles are 9cm and 19 cm. find the radius and the circumference of a circle which has its circumference equal to the circumference of two circles

Answer 1

Total circumference of two circles = 2 pi (r1+r2)
=2 pi (9+19)
2 pi (28)
=176cm
Now the circumference of big circle =176
2 pi r3=176
r3=176/2 pi =28
Another method
2 pi (r1+r2) =2 pi r3
r1+r2=r3
9+19=r3
R3=28cm

Answer 2

$\huge\tt{Required\:Answer}$

According to question:

The radii of two circles are 9cm and 19 cm.

Find the radius and the circumference of a circle which has its circumference equal to the circumference of two circles.

Find

Find the radius and the circumference of a circle.

Circumference of a circle = 2π × r

• 1 st circle circumference = 2π × 19

• 2 nd circle circumference = 92π × 9

• 3 rd circle circumference = r 2π × r

= (2π × 19) + (2π × 9) = (2π × r)

= 2π × (19 + 9) = 2π × r

= r = 19 + 9

= r = 28 cm

As a results, the radius and the circumference of a circle is 28 cm.