To solve this math problem, you'll want to calculate the cosine of the fraction 17π/12 in radians.
1. First step is to convert the measure from the form of a fraction to a solid real number in radians. You should remember that π is a pre-defined constant in mathematics, roughly equal to 3.14159. Thus, to calculate 17 times π and then divide that product by 12.
2. Now, you need to find the cosine of the angle, which was our original task. In trigonometry, the cosine of an angle within a right triangle is the ratio of the length of the side adjacent to the angle with respect to the length of the hypotenuse.
3. By applying this function, we will get the cosine of the angle, which turns out to be roughly -0.25881904510252063. Thus, cos(17π / 12) equals to -0.25881904510252063.
4. To summarize, we converted the angle to radians, then we took the cosine of that angle, and we found that the cosine of (17π / 12) is -0.25881904510252063.
That is how you would solve for the cosine of the angle 17π / 12.