Chapter 4.6, Problem 77E

To determine

Show that $\frac{d\theta }{dx}$ is equal to

To determine

b)

Show that the condition $y-$ coordinate of $Q$ $f(x)-xf\text{'}(x)$

To determine

c)

Show that the condition $\frac{d\theta }{dx}=0$ is equivalent to

To determine

d)

Conclude that $\Delta QPBand\Delta QCP$ are similar triangle