If the radius of a circular solar cell is increased by a fac

If the radius of a circular solar cell is increased by a factor of 2.9, the area of the cell increases by 131 cm2 . Find the radius (in cm) of the new solar cell.

Solution

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Let the radius of ircular solar cell be r

Given increase in radius be dr = 2.9r

Final radius = r + dr = r + 2.9r = 3.9r

Area of circular cell = Pi * r^2

Area of circular cell after radius increased = pi*(3.9)^2*r^2

Increase in area = pi*(3.9)^2*r^2 - Pi * r^2

=> pi*15.21*r^2 - Pi * r^2

=> pi*14.21*r^2 = 131 cm^2 (Given)

r = 1.713 cm

New Solar cell radius = 3.9r = 6.68 cm

Hence Solved