The area of the circle is increasing at a uniform rate of $2 \mathrm{~cm}^2 / \mathrm{s}$. How fast is the circumference of the circle increasing when the radius $r=5 \mathrm{~cm}$ ?

(a) Find: $\int \cos ^3 x e^{\log \sin x} d x$

OR

(b) Find: $\int \frac{1}{5+4 x-x^2} d x$

Find the vector equation of the line passing through the point $(2,3,-5)$ and making equal angles with the co-ordinate axes.

(a) Find $\frac{d y}{d x}$, , if $(\cos x)^y=(\cos y)^x$.

OR

(b) If $\sqrt{1-x^2}+\sqrt{1-y^2}=a(x-y)$, prove that $\frac{d y}{d x}=\sqrt{\frac{1-y^2}{1-x^2}}$.