Memorise the table: sin0=0,sin30=1/2,sin45=1/2,sin60=3/2,sin90=1\sin 0 = 0, \sin 30 = 1/2, \sin 45 = 1/\sqrt 2, \sin 60 = \sqrt 3/2, \sin 90 = 1sin0=0,sin30=1/2,sin45=1/2,sin60=3/2,sin90=1; cos\coscos mirrors sin\sinsin from the other end (cos0=1,…,cos90=0\cos 0 = 1, \ldots, \cos 90 = 0cos0=1,…,cos90=0); tan=sin/cos\tan = \sin/\costan=sin/cos.