2 trig questions help please?

sinθ is positive when θ is in quadrants I and II, and negative when θ is in quadrants III and IV.

cosθ is positive when θ is in quadrants I and IV, and negative when θ is in quadrants II and III.

Visualize the coordinate system. There are 4 quadrants. I shall enumerate them in a counter-clockwise fashion

starting with lower right, then upper right, upper left and lower left. Now we label the quadrants starting with C in

lower right, A in upper right, S in upper left and T in lower left. C stands for Cosine, A stands for All, S stands

for Sin, T stands for Tangent. The CAST system tells you which functions are positive in that quadrant. Note

that if a given function is positive in a given quadrant, it's reciprocal function is also positive. For example, in

quadrant marked S, sin is pos. and so is csc {= 1/sin}. Functions and their reciprocal functions always have

the same sign since their product is always 1.

Think of points on the unit circle.

x = cos(theta)

y = sin(theta)

cos(theta) is positive X

sin(theta) is negative Y

Quadrant 4: - pi/4

cos(theta) is negative X

sin(theta) is positive Y

Quadrant 2: 3pi/4

cos(280) = 0.1736

sin(280) = -0.9848

And

cos(120) = -0.5

sin(120) = 0.8660