If `x=2cost-cos2t ,\ \ y=2sint-sin2t` , find `(d^2y)/(dx^2)` at `t=pi/2` .

Explanation

To find \(\frac{d^2y}{dx^2}\) at \(t = \frac{\pi}{2}\), we will follow these steps:

### Step 1: Find \(\frac{dx}{dt}\) and \(\frac{dy}{dt}\)

Given:
\[ x = 2 \cos t - \cos 2t \]
...