Find the exact values of sin 2u cos 2u and tan 2u using the

Find the exact values of sin 2u, cos 2u, and tan 2u using the double-angle formulas.

cos u = -4/5 /2 < u <

sin2u=

cos 2u=

tan2u=

cos u = -4/5 /2 < u <

sinu = sqrt(1- cos^2u) = sqrt(1 -(4/5)^2)

= sqrt(9/25) = 3/5 ( +ve as sin is +ve in IInd quadrant)

cos2u = 2cos^2u - 1

= 2(-4/5)^2 -1 = 32/25 -1 = 7/25

sin2u = 2sinucosu =2(3/5)(-4/5) = -24/25

tan2u = sin2u/cos2u

= (-24/25) / (7/25)

= -24/7