Ineed answers for number 17 18 20 and 21 need to have all this done when i leave for class at 11

Given (1+cosx)/(sinx) + (sinx)/(1+cosx) =4, find a numerical value of one trigonometric function of x. a. tanx=2 b. sinx=2 c. tanx=1/2 d. sinx=1/2

Find the value of x for which the lines are parallel.

With finding limits of multi variable !