Given that sin(a)+cos(b)= (3^(1/2))/2 and sin(a)+sin(b)=3/2 Find cos(a-b). Can anyone help me?
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You should know that $\displaystyle \displaystyle \cos{(\alpha \pm \beta)} \equiv \cos{(\alpha)}\cos{(\beta)} \mp \sin{(\alpha)}\sin{(\beta)}$. What can you do with this?
It may also be good to remember that $\displaystyle \cos^{2}(x) + \sin^{2}(x) = 1$
The answer i get is 0.786... but the answer given is 0.5. What answer do you guys get?
Last edited by MichaelLight; Jun 18th 2011 at 06:39 PM.
How did you arrive at that? Please describe your process and let's check it out.
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