Answer the following questions related to angular measure.
a. (i) Define one radian without using the degree measure.
b. (ii) Explain why the radian measure of a full revolution is 2π, starting from the definition given in part (i).
c. (iii) An angle is said to be negative when measured in the clockwise sense. Convert −150o to radians and describe briefly how this angle is represented on the Cartesian plane.