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New Member
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Jul 14, 2012, 01:13 PM
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cos(pi+theta)cos(pi/2-theta)=-1/2sin2theta
Prove
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New Member
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Jul 14, 2012, 01:18 PM
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cos(pi+theta)cos(pi/2-theta)=-1/2sin2theta
Prove
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Uber Member
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Jul 15, 2012, 02:57 AM
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Similar to the previous one, you need to make the angle the same as on the right.
How do you change compound angles to single angles?
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New Member
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Jul 15, 2012, 11:09 AM
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Yah similar
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Uber Member
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Jul 15, 2012, 11:10 AM
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So? Remember that:
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New Member
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Jul 15, 2012, 11:30 AM
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Yes
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Uber Member
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Jul 15, 2012, 11:43 AM
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So... if you expand the left side, what do you get?
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New Member
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Jul 15, 2012, 11:52 AM
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(cos pi)(cos theta) - (sin pi)(sin theta)(cospi/2)(costhet) + (sin pi/2)(sin theta)
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Uber Member
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Jul 15, 2012, 11:56 AM
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Simplify it. There are terms you can, such as
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New Member
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Jul 15, 2012, 12:05 PM
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-1cos(theta)-sin(pi)sin(theta)cos(pi/2)cos(theta)+sin(pi/2)sin(theta)
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Uber Member
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Jul 15, 2012, 12:07 PM
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Originally Posted by sally aa
-1cos(theta)-sin(pi)sin(theta)cos(pi/2)cos(theta)+sin(pi/2)sin(theta)
You wrongly did the substitution...
Erm... don't you know the others?
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New Member
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Jul 15, 2012, 12:44 PM
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-1cos(theta)-0sin(theta)0cos(theta)+1sin(theta)
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Uber Member
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Jul 15, 2012, 10:18 PM
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You can simplify this.
Don't forget the brackets you had. It's supposed to be:
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New Member
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Jul 16, 2012, 10:35 AM
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Okay know what ?
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Uber Member
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Jul 16, 2012, 10:36 AM
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I told you that you can simplify this...
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New Member
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Jul 16, 2012, 11:27 AM
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is going to be 0-2costheta -0-0 =2cos( theta )
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Uber Member
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Jul 16, 2012, 11:29 AM
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New Member
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Jul 16, 2012, 11:42 AM
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-costheta-costheta sinthta -sintheta costheta- sine^2 theta like that
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Uber Member
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Jul 16, 2012, 11:51 AM
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:confused:
Okay, what is:
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