This Is An Example Of A Sum And Difference Problem

Now for this sum and difference problem were working with tangent and with radians. The major difference is a change in formula. First find out two solvable angles that add up to your first angle as you would any problem. Now simplify the angles that you have that add up to your first angle. Now time to plug them into the formula. Add up the tangent of both radian measurements. Divide it by one minus the product of the tangent of both radian measurements. Now convert all radian measurements so they are points on a circle, and simply solve. 

This Is An Example Of A Double Angle Problem

Highlighted in blue is key to how this problem is solved. We change cosine of 2x to a trigonometric function using an identity, which is the second piece highlighted in blue. Now treat the cosine squared as an x squared and factor. You then end up with two factors of the problem and two answers to what cosine of x equals.

This Is An Example Of A Half Angle Problem

Here is another problem where you simply plug in the information. There is a difference however, instead of your first angle being a sin angle its now a cosine angle. So that means a new formula! All it is, is tangent of your first angle divided by two (you don't need to divide it out). Then you plug in the first angle in the formula and find common denominators. Then you cannot simplify any further so here is your solution