The diameters of two given circles are in the ratio 12 : 5 and the sum for their areas is equal to the area of a circle of diameter 65 cm. what are their radius ?
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Answer:
325/34cm
Step-by-step explanation:
area of circle having radius
65/2 cm=πr²
=22/7(65/2)²
=π×65×65/4
now if the ratio of diameters of two circles is 12:5
the ratio of their radius also12:5
let their radius are 12x,5x
sum of their areas
= 22/7(12x+5x)²
=π×17×17x²
=π×65×65/2×2
=x²=65²/(17²×4)
x=√65²/√17²√2²
=65/(17×2)
=65/34
12x=12×65/34
=6×65/17=
390/17cm
5x=5×65/34
=325/34cm
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