Use calculator to help solve trig equation

In this math example, we solve a trigonometric equation involving cosine (cosx) with the help of our calculator. Because our problem starts with cosine on one side of the equation, we begin by applying arccosine (inverse cosine function cos^-1) to both sides of the equation. This produces a value for our angle. We determine the quadrant that this angle lies in and also find the reference angle associated with that angle. Next, we find a 2nd quadrant that will have a solution for our equation and use the reference angle to determine the correct angle for that quadrant. These solutions are then generalized to give "all" solutions to the equation (not just those locate in the interval [0 , 2pi).) by adding the period of cosine (2pi) to the end of each solution multiplied by an integer k.