Mrs. Roy designs designs a window in her son's study room so that room gets maximum sunlight.She designs the window in the shape of rectangle sorrounded by an equilateral triangle.If the perimeter of the window is 12 m, find the dimensions of the window that will admit maximum sunlight into the room



(ii) Sumit has bought a closed cylindrical dustbin. The radius of the dustbin is 'r' cm and height is ‘h’ cm. It has a volume of 20π cm³


(a) Express ‘h’ in terms of 'r',using the given volume.
(b) Prove that the total surface area of the dustbin is 2πr²+40π/r
(c) Sumit wants to paint the dustbin. The cost of painting the base and top of the dustbin is ₹2 per cm² and the cost of painting the curved side is ₹25 per cm².Find the cost in terms of 'r' for painting the outer surface of the dustbin including the base and top.

(d) Calculate the minimum cost for painting the dustbin

Solution

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