Find the exact values of sin(u/2), cos(u/2), and tan(u/2) using the half-angle formulas. cot(u) = 3, < u < 3/2

Lin is writing an equation to model the proportional relationship between y, the total cost in dollars of downloading videos from a website, and x, the number of videos downloaded. she knows that the total cost to download 3 videos was $12. her work to find the equation is shown below. joylin’s work step 1 k= 3/12= 0.25 step 2 y= 0.25x where did joylin make her first error?