Question

Find the exact value of arctan(-1)

Answer 1

-0.785398163 radians

Answer 2

or -45 degrees

Answer 3

It's either -45 degrees or -pi/4 radians

if the angle must be between 0 and 360 degrees (or 0 and 2pi), then

arctan(-1) = 315 degrees

arctan(-1) = 7pi/4 radians

and you can find both pieces of info by using this unit circle

http://www.regentsprep.org/Regents/math/algtrig/ATT5/600px-Unit_circle_angles_svg.jpg

Answer 4

you are looking for a point on the unit circle such that the x and y coordinate are the same magnitude, just are different in sign

this is in the 4th quadrant when the angle is 315 degrees