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Mathematics 20 Online
OpenStudy (lukecrayonz):

http://screensnapr.com/v/zn5DFe.png No idea.

OpenStudy (sasogeek):

use the cosine rule, u have the required lengths, the only thing missing is the angle, plug in the values into the equation and solve for \(\theta\)

OpenStudy (anonymous):

what saso said. law 'o cosines for this one

OpenStudy (lukecrayonz):

a^2=b^2+c^2-2(b)(c)cosA

OpenStudy (lukecrayonz):

So then..

OpenStudy (anonymous):

yes but of course you want \[\theta\] not a length

OpenStudy (lukecrayonz):

9=2^2+3^2-2(2)(3)cosX

OpenStudy (anonymous):

what you are looking for is the angle right? so you need to use \[\theta=\cos^{-1}(\frac{b^2+c^2-a^2}{2bc})\]

OpenStudy (anonymous):

or you could use what you wrote above to solve for \[\cos(\theta)\] and then take the inverse cosine to get theta. amounts to the same thing

OpenStudy (sasogeek):

\(a=4\frac{1}{2} \ \ b=2 \ \ \ c=3\)

OpenStudy (lukecrayonz):

I got 70.5

OpenStudy (lukecrayonz):

One last question! Woohoo!

OpenStudy (sasogeek):

looking at the picture, u can simply tell that the angle is greater than 90... 70.5 is definitely not the right answer

OpenStudy (sasogeek):

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