Someone please help!! I’ll give brainliest!

If the value of cos330°is√3/2 then find cos 165°.

Xy x xy if a and b are positive integers such that a*b=9 and b*a=72 what is the value of a/b

The height of a plant, in inches, p years after planting it is given by the polynomial function r(p) = -2p% + 270p. find the height of the plant when p = 90 years.