This is expression for $\tan(a+b+y)$

$$\frac{\tan(a)+\tan(b)+\tan(y)−\tan(a)\tan(b)\tan(y)}{1− \tan(a)\tan(b)−\tan(a)\tan(y)−\tan(b)\tan(y)}$$

I want to represent this with only $\tan(a)$, $\tan(b)$ and $\tan(y)$.

Clearly,I want to replace $1$ with tan functions of these three variables.

I need this answer because thie is from GelfAndSaul Trigonometry Book questions.Pg-145


marked as duplicate by zwim, YuiTo Cheng, Claude Leibovici, cmk, ronno Jun 29 at 17:07

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • $\begingroup$ oh thz... I edited $\endgroup$ – Myat Linn Jun 29 at 10:17
  • 1
    $\begingroup$ Wait, what are you asking? You want to express it in terms of $\tan (a), \tan (b)$ and $\tan (c)$? You already have an expression in them though. $\endgroup$ – Amit Rajaraman Jun 29 at 10:18
  • $\begingroup$ no.... only in terms of tan(a),tan(b) and tan(c)? there is 1. $\endgroup$ – Myat Linn Jun 29 at 10:20
  • $\begingroup$ Even the $1$? $1 = \tan^0 a$. $\endgroup$ – peterwhy Jun 29 at 10:21
  • $\begingroup$ Yep............ $\endgroup$ – Myat Linn Jun 29 at 10:25