Chapter 3.5, Problem 4QC

To determine

The derivatives $\frac{d^{2}y}{d{x}^2}\text{and }\frac{d^{4}y}{d{x}^4}$ when $y=\cos x$ and to find $\frac{d^{40}y}{d{x}^{40}}\text{and }\frac{d^{42}y}{d{x}^{42}}$ when $y=\sin x$.