can someone walk me through the final step of trig substitution?

Question

anonymous · Answer

calc?

anonymous · Answer

as in the step where you take the sin(theta) or whatever trig you're using and apply it to a triangle

anonymous · Answer

yep. calc2

anonymous · Answer

sorry, brb

anonymous · Answer

How about giving us the question, or at least how far you are?

anonymous · Answer

$$\int\limits \sqrt{25x^2-4}/x dx$$

anonymous · Answer

and i'm looking for how to to use a triangle to do the final substitution

anonymous · Answer

let x=5 tan theta

anonymous · Answer

scratch that x=5 sec theta. Is this what you are looking for or are you at another part of the problem?

anonymous · Answer

Scratch that x=2 sec theta. Sorry the 25 distracted me.

anonymous · Answer

the very end. after the trig has been integrated, and you go to substitute variables back in for theta

anonymous · Answer

after integration i have 2(tan(theta)-theta)

anonymous · Answer

Draw a triangle and put your stuff on a triangle. It is difficult to guide you in the middle of a problem and we don't know the work. Watch this tape. I watch it every time I have to do a trig sub. http://www.youtube.com/watch?v=CXKoCMVqM9s&feature=BFa&list=PL590CCC2BC5AF3BC1&index=25

anonymous · Answer

ah that should work. thanks