Question

How did they get this answer??

Answer 1

what answer

Answer 2

I got that the inverse tangent of -10 was equal to -84.3--but the answer is 95.7.

Answer 3

I dont understand what I'm doing wrong,

Answer 4

hmm i think the answer is wrong. i don't think tan^-1 goes beyond 90.

Answer 5

they added 180 degrees to arctan (-10)

Answer 6

because the answer should be in quadrant 2, not quadrant 4

Answer 7

thats the only logical conclusion. do you have all the steps leading up to this point. i am reverse engineering at this point

Answer 8

its to do with the quadrants... tan is negative in the 2nd and 4th quadrants... the solution given is a 2nd quadrant angle

Answer 9

make sure you degrees. OR radians.

Answer 10

so the 2nd quadrant angle is

180 - @ = 180 - 84.3 = 95.7

Answer 11

so perhaps there is a restricted domain or they forgot the 4th quadrant angle

360 - 84.3 = 275.7

Answer 12

the problem here is that if say your terminal point is (-1, 1 ) or (1, -1) , you will get the same arctan

arctan ( 1/ -1) = arctan (-1/1) = arctan (-1)

Answer 13

this 'problem' can be solved with a two argument arctangent function called atan2

http://en.wikipedia.org/wiki/Atan2

or you can just visually inspect your point and make the necessary adjustment