a. -sin x
b. -cos x
c. sin (3pi/2) + sin x
d. -cos x - sin x
e. none of these
2007-03-19 20:42:43 · 5 answers · asked by Wally 1 in Science & Mathematics ➔ Mathematics
sin (a+b)=sin a *cos b+sin b *cos a
so
sin [(3pi/2)+x]=sin (3pi/2)cosx+sin xcos(3pi/2)
=-cosx
b
2007-03-19 20:48:45 · answer #1 · answered by djin 2 · 0⤊ 0⤋
3 pi/2
= 3(180)/2
= 270
We know that sin(270 + x) lies in the fourth quadrant, and in the fourth quadrant, sin is negative. Also we take the friendly ratio(cos), because we have 270 [We take the friendly ratio whenever we get 90 or 270].
therefore... sin(270 + x)
= -cosx
2007-03-19 20:50:19 · answer #2 · answered by Alan 2 · 0⤊ 0⤋
sin[(3pi/2)+x]
= sin(3pi/2)*cos x + cos(3pi/2)*sin x
= -cos x ...........(sin(3pi/2)=-1, cos(3pi/2)=0)
b. -cos x
2007-03-19 20:59:08 · answer #3 · answered by irfan 3 · 0⤊ 0⤋
sin[3π/2 + x] = sin(3π/2).cosx + cos(3π/2).sinx
= - cos x
ANSWER b
2007-03-19 20:51:50 · answer #4 · answered by Como 7 · 0⤊ 0⤋
#c...
like bush, i am a c and d student......
2007-03-19 20:51:56 · answer #5 · answered by Anonymous · 0⤊ 0⤋