Question

The radii of two circles are 12cm and 4cm respectively. The radius of the circle which has circumference equal to sum of the circumference of the circles is

Answer 1

For circle 1,
radius = 12cm
Circumference = 2×pi×r
= 2×22/7×12
= 528/4cm
For circle 2,
Radius=4cm
Circumference=2×pi×r
=2×22/7×4
= 176/7cm
Sum= 528/7 + 176/7
= 704/7
Therefore,
2×pi×r = 704/7
2×22/7×r = 704/7
44×r = 704/7×7
r = 704/44
r =16
Radius of new circle which has circumference equal to sum of the two circles is 16cm.

Answer 2

The radius of the circle is $\frac{704}{44}$.

Step-by-step explanation:

Given:

The radii of two circles are 12 cm and 4 cm respectively. The radius of the circle which has circumference equal to sum of the circumference of the circles is

Solution:

Radius of circle 1 = 12 cm

Circumference of the circle = $2 \pi r$ = $2 \pi \times 12$ = $\frac{528}{4}$

Radius of circle 2 = 4 cm

Circumference of the circle = $2 \pi r$ = $2 \pi \times 4$ = $\frac{176}{7}$

Sum of the circumference = $\frac{528}{4} + \frac{176}{7} = \frac{704}{7}$

Radius of the circle:  2πr = $\frac{704}{7}$

r  = $\frac{704}{44}$

To know more:

Find the circumference of the circles of following radii. a) 7 cm b) 10.5 cm c) 21 m

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