Find cos(u/2) if sin u = -0.085 and u is in Quadrant-IV. cos(u/2) =
cosu = √[1 - (-.085)^2] = about .99638
cos(u/2) = ±√[(1 + cosu) / 2 ] = ±√[(1 + .99638) / 2] = about ± 0. 999
But, if u lies in Q4, then u/2 lies in Q2.....and the cos is negative in that quadrant.....so
cos(u/2) ≈ -0.999