quick question

is 1 - tan^2 x/1 + tan^2x = cos2x? Why is it so if yes?

Question

quick question

is 1 - tan^2 x/1 + tan^2x = cos2x? Why is it so if yes?

anonymous · Answer

@rational

rational · Answer

write tan^2 as sin^2/cos^2 and keep simplifying

anonymous · Answer

oh okay sorry.. another one is

cos^2x - sin^2x = 1 - tan x?

rational · Answer

$$\large \begin{align} 
\dfrac{1-\tan^2x}{1+\tan^2x}&=\dfrac{1-\frac{\sin^2x}{\cos^2x}}{1+\frac{\sin^2x}{\cos^2x}}\~\
&= \dfrac{\cos^2x-\sin^2x}{\cos^2x+\sin^2x}\~\
&=\cdots
\end{align}$$

anonymous · Answer

I did not write down cos^2 x - sin^x/cos^x + sin^x formula :(

anonymous · Answer

Is there any identity for root1+sinx + root1-sinx?

rational · Answer

$$\large \sqrt{1+\sin x} + \sqrt{1-\sin x}$$



like that?

anonymous · Answer

yeah!

rational · Answer

it wont simplify i guess http://www.wolframalpha.com/input/?i=alternate+forms++ \sqrt{1%2B\sin+x}+%2B+\sqrt{1-\sin+x}

anonymous · Answer

hang on lemme use the equation thing on openstudy.. sec

rational · Answer

kk