A man builds a circular pool of radius 5 m inside a circular garden of radius 12 m. In order to compensate the area lost due to the construction of pool, he extends the radius by 'r' m while keeping the garden still circular, so that the area of the garden remains the same. The value of r (in m) is
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Original area of the garden: 1 2 2 × π = 1 4 4 π sq. m
Area of the pool: 5 2 × π = 2 5 π sq. m
Area of the extended garden (incl. pool): 2 5 π + 1 4 4 π = 1 6 9 π sq.m
And 1 6 9 = 1 3 2 , so r = 1 3 − 1 2 = 1 .