What is the difference between 3pi2 and pi2 Dont they both

What is the difference between 3pi/2 and -pi/2? Don\'t they both = 270 degrees? I\'m working on a trig problem where I have to find 3tanx = -3 in the range (-pi/2, 3pi/2).

Solution

3pi/2 is 3X90=270 degrees

- Pi /2 = 270 degrees from counterclock wise direction and -90 degrees from clock wise direction.

3 tanX = -3 implies tanX = -1

X = 45 degrees from clock wise direction or tan (360 - 45) = tan (-45)

ie, tan(315) = -1

ie, 2pi - pi/4 = 7pi / 4