Chapter 14 Trigonometric Graphs, Identities, and Equations - 14.6 Apply Sum and Difference Formulas - 14.6 Exercises - Problem Solving - Page 954: 43a

$\frac{f\frac{\tan\theta-\tan t}{1+\tan\theta\tan t}+f\tan t}{h\tan\theta}$

Applying the difference formula for the tan function we get: $\frac{f(\tan(\theta-t)+f\tan t}{h\tan\theta}=\frac{f\frac{\tan\theta-\tan t}{1+\tan\theta\tan t}+f\tan t}{h\tan\theta}$