Question

hey what is tan(45+a) equal to?

Answer 1

how does this (1 - tan^2a)/(1+tan^2a) cos 2a?

Answer 2

(1 - tan^2a)/(1+tan^2a) = cos 2a?

Answer 3

\[ \tan (a + b) = \frac{\tan a + \tan b}{1 - \tan a \tan b}\]

Hmm that's the formula. One thing you can do is use this \(\large \tan a = \frac{\sin a}{\cos a}\)

\[\frac{1 - \frac{\sin^2a}{\cos^2a}}{1 + \frac{\sin^2a}{\cos^2a}}\]I hope you can do the algebra from here.

Answer 4

ishaan
do we expand the 1 into sin^2a +cos^2a?

Answer 5

yeah! :-D

Answer 6

can you expand this out
cause i don't really get it

Answer 7

okay, i will try.
\[\large \frac{\frac{cos^2a - \sin^2a}{\cos^2a}}{\frac{\cos^2a+\sin^2a}{\cos^2a}}\]
\[\Large \frac{\frac{cos^2a - \sin^2a}{\cancel\cos^2a}}{\frac{1}{\cancel \cos^2a}}\]

\[\cos^2a - \sin^2a = \cos 2a\]

Answer 8

oh i see
thank you very much

Answer 9

no problem

Answer 10

hey ishaan
don't we get 2cos2a then and not 2/cos2a

Answer 11

no i think you forgot the real equation it's \(2 \frac{1 +tan^2a}{1 - tan^2a}\)