If `x=asec^3theta,y=atan^3theta,` find `(d^2y)/(dx^2)` at `theta=pi/4`

Explanation

To find \(\frac{d^2y}{dx^2}\) at \(\theta = \frac{\pi}{4}\) given \(x = \sec^3 \theta\) and \(y = \tan^3 \theta\), we will follow these steps:

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

1. **Differentiate \(y\) with respect to \(\theta\)**:
\[ y = \tan^3 \theta \]
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