If cos degree equals to 0.8641

What is Sin degree?

I have no idea how to find this.
Please help me. Thank you

2 answers

cos^2+sin^2=1

sinDegree=sqrt(1-cos^2degree)
I recognize .8641 as an approximation to √3/2
if cos x = √3/2
x = 30°
sin30° = 1/2 or .5

using your .8641
sinx = .5033