So i'm not the best at math so can i get some with this plz? you!

Aparallel system functions whenever at least one of its components works. consider a parallel system of n components, and suppose each component works independently with probability 0.5. find the conditional probability that component n works given that the system is working

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

Which of the following would be a good name for the function that takes the weight of a box and returns the energy needed to lift it?