Ineed i am run down and sick and my mind is not working right at the moment so a lil

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

At the beginning of year 1, carlos invests $600 at an annual compound interest rate of 4%. he makes no deposits to or withdrawals from the account. which explicit formula can be used to find the account's balance at the beginning of year 5? what is, the balance?

Write the slope intercept equation for line ab.