Question

If sin x = .21,what is cos x?

Answer 1

one way to solve this would be to use the pythagorean identity of sin and cos:

sin^2 + cos^2 = 1

Answer 2

sin^2x+c0s^2x=1
sin^2x=1-cos^2x
(.21)^2=1-cos^2x
0.0441=1-cos^2x
cos^2x=1-0.o441
cos^2x=0.9559
cosx=+-0.9777