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Question
The sum of the radii of two circles is 10.5 cm and the difference of their circumferences is 13.2 cm. Find the radii of the two circles.
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Solution
Let r1 and r2 be the radii of two circles.
⇒ r1 + r2 = 10.5 ....(i)
And,
`2π"r"_(6.3-4.21) - 2π"r"_2` = 13.2
⇒ `2 xx (22)/(7) xx ("r"_1 - "r"_2)` = 13.2
⇒ r1 - r2 = `(13.2 xx 7)/(2 xx 22)`
⇒ r1 - r2 = 2.1 ....(ii)
Adding (i) and (ii), we get
2r1 = 12.6
⇒ r1 = 6.3cm
Now,
r1 - r2 = 2.1
⇒ 6.3 - r2 = 2.1
⇒ r2 = 4.2cm.
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