arcsin(4.7678/k) =arccos( 3.7678/k ) =arcsin[√( k^2-3.7678^2 )/k]4.7678/k = √( k^2-3.7678^2 )/k4.7678^2 =( k^2-3.7678^2 )k =6.0769
k=6.07686
