Question

the radii of two circles are 19 cm and 9cm respectively find the radius of the circle whose circumference is equal to the sum of the circumference of the two circles ​

Answer 1

Hey mate here's your answer.

Let r be the radius of the circle whose circumference is equal to the sum of circumference of two circle of radii 19cm and 9cm.

2πr = 2π(19) +2π(9)

=> r = 19 + 9 = 28

hence, the radius of the new circle is 28 CM.

Answer 2

radius of first circle = 19 CM

circumference of first circle = 2πr1

radius of second circle = 9cm

circumference of second circle =2πr2

now

circumference of both circle=2πr1+2πr2

= 2π(r1+r2)

=2 ×22/7 (19+9)

=2×22/7 (28)

= 2×22×4

= 176cm

Since circumference of both circle = circumference of bigger circle

2πr = 176cm

2×22/7×r = 176cm

44/7 r =176

r= 176 × 7

—

44

r= 28 cm

Hence the radius of bigger circle= 28cm.

hope it helps u