How tall is a bridge if a 6 foot person is standing 100 feet away can see the top of the bridge at an angle of 30 to the horizon?

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

Any is very appreciated! (picture is provided below)not sure how to do this at all won't lie

Type the correct answer in each box. use numerals instead of words. if necessary, use / for the fraction bar. consider the given table.