Hello,
cos 160°=-q
cos 20°=-cos 160°=q
sin 20°=√(1-q²)=sin 160°
tan -20°=tan 160=√(1-q²)/-q
cos 70°=sin 20°=√(1-q²)
The proportion pop/total = 5/7 is presumed to hold for the next 500 songs.
pop/500 = 5/7
pop = 500*5/7 ≈ 357
357 of the next 500 songs downloaded are expected to be pop songs.
