Most problems use θ∈{30,45,60}\theta \in \{30, 45, 60\}θ∈{30,45,60} so that tanθ\tan\thetatanθ takes clean values. Being fluent in tan30=1/3\tan 30 = 1/\sqrt 3tan30=1/3, tan45=1\tan 45 = 1tan45=1, tan60=3\tan 60 = \sqrt 3tan60=3 is essential.