Please help in maths

Find the slope of the line that contains the following points. r(-2, 4), s(6, -2)

Given sin∅ = 1/3 and 0 < ∅ < π/2 ; find tan2∅ a. (4√2)/9 b. 9/7 c. (4√2)/7 d.7/9

Which of the following is the major negative aspect of crossover designs for research studies? a. prohibitive cost b. residual effects c-subject drepout d. incomplete randomization e. large sample size required