Find the exact value of the trigonometric expression given t
Find the exact value of the trigonometric expression given that sin u = 8/17 and cos v = 3/5 . (Both u and v are in Quadrant II.) tan(u + v)
Solution
given sinu = 8/17
cosv =-3/5
given u,v are in QII
now from sin^2 u +cos^2 u=1
(8/17)^2 +cos^2 u =1
cos^2 u = 1 - 64/289
cos^2 u = 225/289
cosu = -15/17 (since u is in QII)
now tan u = sin u/cosu = (8/17)/ (-15/17)
tan u = -8/15
in the same find sinv value and tanv value
sin^2 v +cos^2 v=1
sin^2 v = 1 - (-3/5)^2
sin^2 v = 1 -9/25
sin^2 v =16/25
sinv =4/5 (since v is QII)
tanv = sin v/cosv =(4/5) /(-3/5)
tan v = -4/3
now tan(u+v) =( tanu + tanv) / (1 -tanu.tanv)
= ( -8/15 + -4/3 ) / (1 - (-8/15) (-4/3) )
= [ (-8 -12)/15 ] / [ (1- 32/45) ]
=(-20/15) /(13/45)
= (-20*3)/13
=-60/13
