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    https://a086a5a2f39bda93734c56a63fab...%20Edexcel.pdf


    Hi, for the last question how would you know what the radius and height is for the cone?
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    (Original post by imran_)
    https://a086a5a2f39bda93734c56a63fab...%20Edexcel.pdf


    Hi, for the last question how would you know what the radius and height is for the cone?
    Say R is the point on the x-axis vertically below P. Then the cone is formed by rotating the triangle PQR 360 degrees about the x-axis.

    Try and imagine rotating this triangle and think about how the cone is formed.

    Post your thoughts if you're still unsure.
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    The radius is the y coordinate and the height is the difference in the x coordinates. I just picture the shape rotating about the x axis.
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    integrating the equation y=3^x will get you the equation of R+S

    You can then find out the area of S by saying its a cone, made up of radius = 9 and height = 2- (x-coordinate of Q)

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