trig idents

[Phymath]

this had some projectile physics but the problem boils down to...

show...
\frac{1-sin \beta}{cos^2 \beta} = \frac{1}{1+sin \beta}

no idea..

[Doc Al]

Try using the simplest trig identity of them all:
\sin^2 \theta + \cos^2 \theta = 1

[gravenewworld]

worse comes to worse, you could always represent cos and sin in their complex number forms and just treat the problem as a simple algebra problem.

[Gokul43201]

Use Doc's suggestion and the answer will pop right out in just one step.

PS : Next time, post a question like this under Pre-calculus math.