If x = a cos θ + b sin θ, y = a sin θ – b cos θ, show that

If sin [cot^-1 (x + 1)] = cos (tan^-1 x), then find x.

OR

If then find x.

If then find

The side of an equilateral triangle is increasing at the rate of 2 cm/s. At what rate if its area increasing when the side of the triangle is 20 cm?

Find :