When does cosecant=2?

1 Answer
Mar 19, 2018

# x in {pi/6, (5pi)/6 } + 2pi n# where # n in mathbb{Z}#.

Explanation:

We want to solve when
#csc(x) = 2#

but cosecant is an ugly function. Let's make it into sines and cosines. That's not hard at all:
#csc(x) = 1/sin(x)#
so therefore we want to find when
#sin(x) = 1/2 #

This happens in a 30-60-90 triangle! So we can write down a few times that this happens, based on our knowledge of the unit circle:
#x = pi/6, (5pi)/6, (13pi)/6, (17pi)/6, ... #
i.e.
# x = {pi/6, (5pi)/6 } + 2pi n# where # n in mathbb{Z}#.