Urgent which equation can be used to find the measure of angle bac?

tan−1 = x-1 5/12=x
tan−1 = x-1 12/5=x
cos−1 = x-1 12/13=x
cos−1 = x-1 13/12=x

An office supply company conducted a survey before marketing a new paper shredder designed for home use. in the survey, 80 % of the people who tried the shredder were satisfied with it. because of this high satisfaction rate, the company decided to market the new shredder. assume that 80 % of all people are satisfied with this shredder. during a certain month, 100 customers bought this shredder. find the probability that of these 100 customers, the number who are satisfied is 69 or fewer.