 In this video we provide the solution to question number six from the practice final exam for math 1060 in which case We're asked to solve the equation to cosine of 2 theta equals 1 and do this in degrees So the first thing to do is to solve for the trigonometric function cosine in this situation cosine of 2 theta equals 1 half When does cosine equal 1 half well cosine is positive in the first and fourth quadrant And so we get 2 theta is going to equal 6 to degrees That's when that's when cosine is equal to one half in the first quadrant But we also have any multiple or anything coterminal to that so we can add 360 k to it But also in the fourth quadrant cosine will be one half at the angle which references 60 degrees Which is 300 degrees plus 360 k Then we have to divide the answers by 2 to get theta So 60 divided by 2 is 30 degrees But that also changes the period to be 180 degrees k And then we also to divide 300 by 2 so we get 150 degrees plus Dividing the period also by 2 we get 180 k as well And so looking at the answers there we see that the correct answer would be choice e