Question 29984
y=tanA asking where is tanA=-1?


First, find where tanA=+1, since your calculator stores this value. You get A = 45degrees.


So, where is tan -ve? Answer is in the second and fourth quadrants, so we need the equivalent angle there:


180-45 --> 135degrees
360-45 --> 315degrees


These are the 2 answers within the 0 to 360 degree range.


2. y = 3sin2x


--> 3sin2x = 0
sin2x = 0
2x = 0 or 180 or 360 or 540 or 720
--> x = 0 or 90 or 180 or 270 or 360


These are the 5 answers within the 1 to 360 degree range.


Look at my Lesson on solving Trig equations to understand my method, if you are not sure.


Jon.