Error comments on Stupid Questions February 2015 - Less Wrong

9 Post author: Gondolinian 02 February 2015 12:36AM

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Comment author: Error 03 February 2015 12:21:40AM 2 points [-]

Describing sine and cosine this way, instead of in terms of triangles, suddenly makes their behavior feel much more intuitive to me; on par with the way complex numbers in general suddenly made sense when someone here described multiplication by i as a rotation.

Thanks.

Comment author: gjm 03 February 2015 12:45:27AM 2 points [-]

More elementarily: cos x and sin x are the x and y coordinates of the point on the unit circle at an angle x anticlockwise from the positive x-axis. (I think this is the correct version of the "triangles" definitions.)

Comment author: Viliam_Bur 03 February 2015 10:54:32AM 1 point [-]

If you don't rotate, the cosine is still there; only the sine is zero. So, in some sense, cosine is more fundamental; it was there before the rotation.