Question

quick question

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

Answer 1

@rational

Answer 2

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

Answer 3

oh okay sorry.. another one is

cos^2x - sin^2x = 1 - tan x?

Answer 4

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

Answer 5

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

Answer 6

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

Answer 7

\[\large \sqrt{1+\sin x} + \sqrt{1-\sin x}\]



like that?

Answer 8

yeah!

Answer 9

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

Answer 10

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

Answer 11

kk