Question

Find the radius of a circle whose circumference is equal to the sum of the circumferences of the two circles of diameters 36 cm and 20 cm.

Answer 1

let radius of one circle [r1] =18 cm
radius of 2nd circle [r2] = 10 cm
radius of 3rd circle[r3] = ?
ATQ
C1 + C2 = C3
2лr1 +2лr2 =2лr3
2л (r1 + r2) = 2лr3
18 + 10 = 2лr3/2л
28 = r3
radius of 3rd circle is 28 cm.

Answer 2

Answer:

Step-by-step explanation:

we know that

the circumference of circle = 2πr

where r is the radius

now.

the circumference of circle of radius 15 cm = 2π×15= 30π cm

&

the circumference of circle of radius 18cm = 2π×18 = 36π

According to question

the circumference of circle whose radius is r = 30π+36π = 66π

=> 2πr =66π

=> r = 33 answer