Question

If sin x = .42, what is cos x?

Answer 1

`We\ know:\\\\\sin^2x+\cos^2x=1\to\cos^2x=1-\sin^2x\to\cos x=√(1-\sin^2x)\\\\\sin x=0.42\\subtitute\\\\\cos x=√(1-0.42^2)=√(1-0.1764)=√(0.8236)\approx0.91`