After reading and analyzing a word problem, what is the name of the letter that represents an unknown?

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

In the diagram of circle o, what is the measure of zabc?

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )