Trigonometry: Determine two coterminal angles in radian measure

Determine two coterminal angles in radian measure (one positive and one negative) for each angle. (There are many correct answers. Enter your answers as a comma-separated list.)

(a) 5π/7


(b) π/14

(a) 5pi/7 + 2pi = 5pi/7 + 14pi/7 = 19pi/7 ; 5pi/7 - 2pi = 5pi/7 - 14pi/7 = -9pi/7.

So we have {19pi/7, -9pi/7} as one pair of possible co-terminal angles to 5pi/7.

(b) pi/14 + 2pi = pi/14 + 28pi/14 = 29pi/14 ; pi/14 - 2pi = pi/14 - 28pi/14 = -27pi/14.

So {29pi/14, -27pi/14} is one pair of possible co-terminal angles to pi/14.

In degrees, coterminal angles are 360 deg apart;
in radians, they are 2pi apart.
To get one pos and one neg answer, all you have to do is add and subtract 2pi (or 4pi, or 6pi, ...) from each angle.
(a) 5pi/7 + 2pi
5pi/7 + 14pi/7
19pi/7 <---
5pi/7 - 2pi
5pi/7 - 14pi/7
-9pi/7 <---
(b) do the same thing; 2pi would be 28pi/14