Find the exact value of sin 2pi/3

Express the following as a function of a single angle, cos(60) cos(-20) - sin(60) sin(-20)

The angle of a triangle are given as 6x,(x-3), and (3x+7). find x then find the measures of the angles

Boris needs to buy plastic spoons. brand a has a box 42 spoons for $2.37. brand b has a box of 72 spoons for $3.57. find the unit price for each brand. then state which brand is the better buy based on the unit price. round your answer to the nearest cent.