Question 843891
if sin^-1, x=2 pi/5 find the value of cos^-1
sin^-1(x)=2&#960;/5
cos^1(x)=&#960;/2-2&#960;/5=&#960;/10
check:
sin(2&#960;/5)&#8776;0.951
cos(&#960;/10)=0.951
note: sin(x)=cos(&#960;/2-x)