1.

Find the equation of the tangent and normal to the curve y= 1 + sin 2x at the point x=

.

2.

The volume of a cone V

is given by the formula V=

, where k is constant, r is the radius of the cone and

is a semi vertical angle. Given that r is fixed and

is increasing at a rate of 0.2 radian per second, calculate the rate of change of volume with respect to time when

=

.

================

i think i know how to do, but the problem is

**my answer is not the same as the book's answer. Can someone please tell me where i went wrong ??**
1.

When x=

,

When x=

, y=

equation of tangent :

the book's answer is

so my answer is different from the book's answer in terms of the positive sign and negative sign .....

gradient of normal=

equation of normal:

the book's answer is