What? I understand that this works for -pi/2 - pi/2, but what about the rest of the unit circle? Why are only the first and fourth quadrants mentioned?

https://www.khanacademy.org/math/calculus/limits_topic/squeeze_theorem/v/proof--lim--sin-x--x

Question

What? I understand that this works for -pi/2 - pi/2, but what about the rest of the unit circle? Why are only the first and fourth quadrants mentioned? 

https://www.khanacademy.org/math/calculus/limits_topic/squeeze_theorem/v/proof--lim--sin-x--x

mendicant_bias · Answer

I understand the proof, up until the point that they limit it only to the first and fourth quadrants. What is the use of this whole proof if it is only applicable within $$(-\pi/2, \pi/2)$$???

anonymous · Answer

sinx/x is need when x tends to 0.

mendicant_bias · Answer

Oh, yeah, totally overlooked that. Thanks. *facepalm*