jika sin x = 3 cos x dan x terletak di kuadran tiga maka nilai sin x × cos x =…

Trigonometri

sin x = 3 cos x , x di kd III
sin x/cos x = 3
tan x = 3 = 3/1 = y/x
misal y= 3, x = 1
r² = x² +y²
r² = 1²+3² = 10
r = √10  atau r = - √10
.
di KD iii --> sin x < 0 dan cos x< 0
sin x  = - y/r,
cos x = - x/r
.
sin x . cos x  = -y/r  . -x./r
sin x . cos x = (xy)/r² = (1)(3)/(√10)²
sin x. cos x = 3/10 = 0,3