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secondary 4 | A Maths

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Since the base of the bigger cone is 20, and height is 60 (ratio is 3), this means that the height of the smaller cone is 3 times its base also, hence 3r. From there you can solve for part (i).

You have the formula of the S.A. of cylinder (2*pi*r^2+ 2*pi*r*h). Substitute h as the expression in (i), and you get the answer for part (ii).

(iii) You should be able to do this question with differentiation. So is part (iv)

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