0
$\begingroup$

Prove the following statement: $$1+\tan^2a=\dfrac{1}{\cos^2a}$$

I tried but I failed to find answer cause I don't know how to prove trigonometric equalities.

Thank you for your help!

$\endgroup$
3
  • 6
    $\begingroup$ Do you know, $\tan A=\frac{\sin A}{\cos A}$ and $\sin ^2A+\cos^2A=1$ $\endgroup$
    – lab bhattacharjee
    Commented Dec 14, 2013 at 10:59
  • $\begingroup$ yes i know those rules $\endgroup$
    – user115729
    Commented Dec 14, 2013 at 11:04
  • $\begingroup$ Never forget this last one ! It is one of the most used in trigonometry. $\endgroup$
    – Claude Leibovici
    Commented Dec 14, 2013 at 11:52

1 Answer 1

Reset to default
4
$\begingroup$

Hint:

$$\color{blue}1+\color{red}{\tan^2a}=\color{blue}{\dfrac{\cos^2a}{\cos^2a}}+\color{red}{\dfrac{\sin^2a}{\cos^2a}}$$

$\endgroup$
1
  • $\begingroup$ aaa!! didnt think about it!! $\endgroup$
    – user115729
    Commented Dec 14, 2013 at 11:05

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .