5cos( x + pi / 2 ) = ? explain steps please =/?

2007-09-16 13:33:16 · 2 answers · asked by Sibel 1 in Science & Mathematics ➔ Mathematics

5 [ cos x cos π/2 - sin x sin π/2 ]
5 [ 0 - sin x ]
- 5 sin x

2007-09-16 20:12:47 · answer #1 · answered by Como 7 · 1⤊ 0⤋

cos(A+B) = cosAcosB - sinAsinB

cos(x + (pi/2)) = cos(x)cos(pi/2) - sin(x)sin(pi/2)
= -sin(x)

5cos(x + (pi/2)) = -5sin(x)

2007-09-16 20:40:52 · answer #2 · answered by gudspeling 7 · 0⤊ 0⤋

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