Diketahui sin ∝ =4/5 dan cos ∝ =7/25, ∝ dan β di kuadran I. hitInglah nilai : ∝ cos β + cos ∝ sin β ?

trigonometri
soal di ubah
sin α = 4/5, cos β = 7/25 dan α,β di kuadran I
nilai sin α cos β + cos α sin β  =..
.....
sin α = 4/5
sin α = y/r = 4/5 -->triple pitagoras x,y,r = 3,4,5
α di kuadran I , cos α > 0 --> cos α = x/r= 3/5

cos β = 7/25
cos β = x/r --> triple pitagoras x,y,r = 7,24,25
sin β = y/r = 24/25

nilai sin α cos β + cos α sin β = (4/5)(7/25) + (3/5)(24/25)
= 28/125 + 72/125
= 100/125
= 4/5