express sin(y-270) in terms of a function of y
2006-11-20 13:42:59 · 4 answers · asked by topi5389 3 in Science & Mathematics ➔ Mathematics
sin(y-270)
Is that sin(y - 270°)?
If so sin(y - 270°) = siny cos270° - cosy sin270°
= siny * (0) - cosy * (-1)
= cosy
2006-11-20 13:46:44 · answer #1 · answered by Wal C 6 · 0⤊ 0⤋
You don't have to go roundabout.
y - 270 is the same as y + 90.
Just look at graphs of sin and cos and you will see that cos crests 90 degrees before sin does, and crosses the x-axis 90 degrees before sin does, and so on.
So,
sin(y + 90) = cos(y)
2006-11-20 21:52:40 · answer #2 · answered by ? 6 · 0⤊ 0⤋
Use the identitiy sin(a-b) = sin a cos b - cos a sin b.
So sin(y-270) = sin y cos 270 -cos y sin 270 = cos y.
2006-11-20 21:50:21 · answer #3 · answered by steiner1745 7 · 0⤊ 0⤋
girl use a calculator i could do it in my head!
2006-11-20 21:45:50 · answer #4 · answered by Anonymous · 0⤊ 0⤋