How do you evaluate arctan(1) without a calculator?

Question

amistre64 · Answer

arctrig function take ratios and give back angles:

si if you know which angle has a tangent of 1, your good to go:

tan-1(1) = a

tan(a) = 1

amistre64 · Answer

|dw:1318289505699:dw|

anonymous · Answer

oh! thank you. What I don't get is how you figure out the value of a. I understand the triangle you drew but is a 45 b/c it's a 45, 45, 90 triangle?

amistre64 · Answer

yep, and as long as you "know" the triangle; you can remember the angle; otherwise, you really need a calculator

anonymous · Answer

http://sk19math.blogspot.com/2007/05/special-angles-in-trigonometry.html

amistre64 · Answer

trig is all about memorizing things that you really never use, since most trig stuff is irrationals and have to be calculated by machine for accuracy.  Or you can sum up the sequences if your really desparate

amistre64 · Answer

its useful to write out the triangle and apply the "trig" function that is being addressed and see if it looks familiar

anonymous · Answer

thank you! I've been battling with these kinds of problems all night. I'm going to go try the other one again!