Find two exact values of sin(cosˉ¹√5/6)
cos^-1 (√5/6)
is an angle Ø so that sinØ = √5/6
sketch a right-angled triangle with hypotenuse 6, and opposite side √5
by Pythagoras the adjacent side is √31
then cosØ = √31/6
so sin(cosˉ¹√5/6) = √31/6