User:Xiong/Trig

Basic relationships
From the two identities above, the following table can be extrapolated. Note however that these conversion equations may not provide the correct sign (+ or &minus;). For example, if sin θ = 1/2, the conversion in the table indicates that $$\scriptstyle\cos\theta\,=\,\sqrt{1 - \sin^2\theta} = \sqrt{3}/2$$, though it is possible that $$\scriptstyle\cos\theta \,=\, -\sqrt{3}/2$$. More information would be needed about which quadrant θ lies in to determine a single, exact answer. This only applies to the transformations with the square root function.