# Past Papers’ Solutions | Cambridge International Examinations (CIE) | AS & A level | Mathematics 9709 | Pure Mathematics 1 (P1-9709/01) | Year 2011 | Oct-Nov | (P1-9709/13) | Q#10

Hits: 328

Question The diagram shows the line and the curve , meeting at and .

i.       Find the area of the shaded region.

ii.       Find the volume obtained when the shaded region is rotated through 360 about the y-axis.

Solution

i.

It is evident from the diagram that; To find the area of region under the curve , we need to integrate the curve from point to along x-axis.   Rule for integration of is:  Rule for integration of is: Rule for integration of is:            ii.

It is evident from the diagram that; Expression for the volume of the solid formed when the shaded region under the curve is rotated completely about the y-axis is; We have equations of curve and line as;  To find volume from rotation about y-axis we need to rewrite these equations in terms of y.

First equation of curve;    Now equation of line;  Now we can find the required volume;      Rule for integration of is:  Rule for integration of is:          