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Mathematics 22 Online
OpenStudy (anonymous):

Quick question on the multiplication of trig functions.

OpenStudy (anonymous):

I was getting the determinant of a matrix.This left me with \[((\cos(3t).3\cos(3t))-((\sin(3t).-3\sin(3t))\]

OpenStudy (anonymous):

Just wondering how do I multiply this out

OpenStudy (anonymous):

Wolfram doesn't break it down for me. Just gives me the result.

OpenStudy (amistre64):

3cc--3ss = 3(c^2+s^2)

OpenStudy (amistre64):

using the trig id that s^2+c^2 = 1 .... id say that leaves 3

OpenStudy (anonymous):

@amistre64 Are you saying 1sin^2+1cos^2=1???

OpenStudy (amistre64):

i hope so .... :)

OpenStudy (anonymous):

Well the answer is 3 but the calculator says otherwise

OpenStudy (anonymous):

I'm getting 0.98...........

OpenStudy (anonymous):

Which I guess is close to 1, I guess.

OpenStudy (amistre64):

its prolly due to input errors

OpenStudy (amistre64):

the (3t) part is useless jargon in this case

OpenStudy (amistre64):

sin.sin=sin^2 cos.cos=cos^2 sin^2+cos^2=1

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