What equation i should use for this problem

(a) compute the maclaurin polynomial m2(x) for f(x) = cos x. (b) use the polynomial of part (a) to estimate cos π 12. (c) use a calculator to compute the error made using the estimate from part (b) for the value of cos π 12. remember that the error is defined to be the absolute value of the difference between the true value and the estimate.

What is the 12th term of b(n)=-4-2(n-1)

If a || b and e || f , what if the value of y ?