The sum of the radii of two circles is 140cm and the difference of their circumferences is 88cm. Find the diameters of the circles.


Let radius of first circle = r1cm


Let radius of second circle = r2cm


So,


r1 + r2 = 140cm …. (i)


2πr1 – 2πr2 = 88cm



r1 - r2 = 14cm …. (ii)


By adding equation 1 & 2



r1 = 77cm


From equation 1


77 + r1 = 140 cm


r2 = 140 – 77 = 63cm


r2 = 63cm


So,


Diameter of first circle = 2×r1 = 2×77 = 154cm


Diameter of second circle = 2×r2 = 2×63 = 126cm


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