Question 1174709
<pre>
That's wrong.

Since we want inverse trig functions to be functions, they must always
have a unique value, so the rule that's chosen by mathematicians is:

Inverse sine, cosine and tangent functions are restricted so that they can only
be the smallest possible angle in absolute value, and if that results in a choice
between a positive or a negative angle, the positive angle is chosen.

So sin<sup>-1</sup>(1/2) = 30°

All other angles which have sine equaling 1/2 are larger in absolute value than
30°, so 30° is the only answer.

Edwin</pre>