Math Help - Identitiess!

1. Identitiess!

Show that 1+tan^2t = sec^2t and show that sin2t=2sintcost

Thankss!

2. Originally Posted by lolalovepink
Show that 1+tan^2t = sec^2t and show that sin2t=2sintcost

Thankss!
$1+tan^{2}t=1+\frac{\sin^{2}t}{\cos^{2}t}=\frac{\co s^{2}t+\sin^{2}t}{\cos^{2}t}=\frac{1}{\cos^{2}t}=\ sec^{2}t$
for the $\sin 2t=2\sin t\cos t$,I assume you know that $\sin x+y=\sin x\cos y+\cos x\sin y$. Then it would be directly followed. If you have not learned this yet, it would become a very complex geometric proof.