Pls awnser i will give brainliest

Express the following as a function of a single angle. cos(60) cos(-20) - sin(60) sin(-20)

Using only the digits 5, 6, 7, 8, how many different three digit numbers can be formed if no digit is repeated in a number?

C. using a standard deck of 52 cards, the probability of selecting a 4 of diamonds or a 4 of hearts is an example of a mutually exclusive event. true of false