(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Differentiate twice: z = sinx

2. Relevant equations

Product rule

Chain rule

3. The attempt at a solution

dy/dx = dy/dz * dz/dx

dy/dx = dy/dz * cosx

Using the product rule:

d^2y/dx^2 = d^2y/dz^2 * cosx - dy/dz * sinx

According to the answer in the book the answer is: d^2y/dx^2 = d^2y/dz^2 * cos^2x - dy/dz * sinx but I don't see how.

Thanks for any help.

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# Differentiating twice with respect to x

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