Why is sin(theta)=(2/7) in second quadrant?

Answer 1

The sine function is positive in quadrants I and II, and negative in quadrants III and IV. Since sin(θ) = 2/7, it must be quadrants I or II. The only way to narrow it to Q II is if you are given another trig function for θ, such as cos(θ). The cosine is positive in Q I but negative in Q II, so if cos(θ) is negative, then sin(θ) must be in Q II.