If you have a calculator, you can use the inverse cos " cos⁻¹ " key. Many upper level books write that as Arccos so as not to confuse you with a negative exponent. We do that because if you take the cosine of any angle, and then the inverse cosine of any angle, it leads you back to the original angle. Think of it as a big "UNDO" button.
To one decimal place, that result is 61.6 degrees.
The answer is 8.88; You look at the number that comes after the second number (the second place after the decimal) and if that number is 5 or above then you round the second number up. (Sorry if it doesn't make sense, but that's the best I can explain it).
