It is quite easy to find an answer for the equationfor example. We finddegrees. However this is not the only answer. Because of the periodicity of the cosine curve, repeating every 360 ^{o } and symmetry of the cosine curve aboutetc, the following are also solution:

Suppose instead we have to solve the equation

Now we can write down lots of equations to solve, again using the symmetry of the cosine curve:

Normally we are given a range in which the values ofmust lie. If the range is in this case 0-360 ^{o }, then is this case only the first four values ofwould be the required solutions.

Example: Find all the solutions ofin the range 0 ^{o }-360 ^{o }.

The graph of sin has symmetry in the lineswe have

sodegrees.

degrees.

degrees.

degrees.