SHORTZ: Inverse function is it. RASCOE: OK, ah - so, as it turns out, that is not it. And y'all did not hesitate to give us a quick math lesson, specifically in trigonometry.

The inverse functions of sin, cos and tan are sin⁻¹, cos⁻¹ and tan⁻¹. To work out \(Ɵ\), calculate sin⁻¹ or cos⁻¹ or tan⁻¹ of the fraction on the right-hand side.

The second solution is excluded by the traditional definition of the inverse cosine function (which, for arccos(x) = y, specifies a range of 0 <= y < pi so that the inverse cosine function can ...