# trig

• January 13th 2009, 04:46 PM
shanzwhaat
trig
$sec^2x * tanx = 2tanx$
in [0, 360) interval
find degree of x

Do I subtract 2tanx then use tan^2+1 = sec?
• January 13th 2009, 04:55 PM
vincisonfire
$\frac{sin(x)}{cos^3(x)}= 2\frac{sin(x)}{cos(x)}$
$\frac{1}{2} = cos^2(x)$
$\pm \sqrt{\frac{1}{2}} = cos(x)$
Can you find the answer now?
• January 13th 2009, 05:01 PM
shanzwhaat
Yes, thanks.. but i did it like this and it worked....
$sec^2x * tanx = 2tanx$
and i divided tanx from the both sides and got..
$tan^2x+1=2$ then..
$tan^2x=1$and finally..
$tanx=+/-1$

That way can work too right?
• January 13th 2009, 05:04 PM
vincisonfire
Of course it is even better. I have a tendency to complicate things.
• January 13th 2009, 05:05 PM
shanzwhaat
Hhaha okay.. thank you so much for your help, it actually helped me to get to that step haha.