Answer the following questions with reference to the unit circle.
a. (i) Explain what is meant by the “terminal point” corresponding to an angle θ on the unit circle.
b. (ii) Describe how the signs of sinθ and cosθ are determined from the position of the terminal point in the four quadrants.
c. (iii) Without using any numerical calculation, justify that sin150∘>0 while cos150∘<0.