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anonymous

  • one year ago

Prove Identity: sin(x-pi/2)=-cosx I have been trying to figure out this problem for over an hour. I understand most of the basic concept, but this is stumping me for some reason.

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  1. anonymous
    • one year ago
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    Two methods - but the first one is not as much of a method as it is a "here's what this thing looks like". So here's what this thing looks like: |dw:1435629703401:dw|

  2. anonymous
    • one year ago
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    But of course all of this looks complicated and although it would be somewhat plausible to solve it geometrically it would be quite pointless. The simple way to do it is to simply apply the formula for sin(a-b)=sin(a)*cos(b) - sin(b)*cos(a).- where b=pi/2. Pro hint: You can see from the trigonometric circle that cos(pi/2)=0 and sin(pi/2)=1.

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