What is the margin of error for a sample statistic for a population of 7.75

(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.

Don't know how to find x given these segment lengths

For what values of the variable x is the expression square root of 7x+14+ square root of 7-x a real number?