The cosecant is the reciprocal of the sine function. That means you invert all the fractions and you divide 1 by the non-fractions.
csc(0°) = 1/0
csc(30°) = 2/1 = 2
csc(45°) = (√2)/1 = √2
csc(60°) = 2/√3
csc(90°) = 1/1 = 1
