1. trigonometric substitution

$\displaystyle \int\ dx /\sqrt(25+x^2)\\$ on the interval (0,1). So I use x=5tany, and dx=5sec^2y...
I got it down to integral $\displaystyle 5sec^2y / \sqrt(25(1+tan^2y)\$
and then substituting sec^2 for y=tan^2y...left me with 5sec^2y/5sec^2y..so Im left with the integral of 1, right?

Then I get y+C....but how do I solve for y...I'm really confused, did I do all the above steps the right way?

2. x = 5tan(y) -->
x/5 = tan(y) -->
arctan(x/5) = y

3. thank you so much, I get it! how did I not see that...

4. Calculus makes people do funny things! I've had students forget which quadrants are which, that the product of two negatives is postive, etc...