Khan/khan-exercises — Issue #5782: Inverse trig functions - videos do not explain the concept
Author: KhanBugz
Created: 2011-11-08 05:43:51+00:00
State: open
Labels: firefox, win7

Reporter: darkwolfn1@gmail.com

Sal's Inverse trig videos depend entirely on identifying the angle by recognizing either (30,60,90) or (45,45,90) triangle ratios.

However, I feel that I still don't understand the concept of inverse trig functions or how to apply them to determine any other angles (say if the angles were 13, or 77). And I certainly don't understand any of the mathematics concepts used to determine it in this case. The exercises only reinforce this.

I feel that these exercises and videos don't give a proper understanding of arcsin / arccos / arctan. All they do is promote using 30,60,90 triangle recognition as a short cut to the problem.

There are a number of questions on the arcsin video that also are asking about this issue (none of which have answers) so I know I'm not the only one.

Are there videos further in the calculus play list that cover this or can this issue be addressed?

[inverse_trig_functions.html?seed=54&problem=0](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/inverse_trig_functions.html?seed=54&problem=0&debug)

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