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Mathematics 17 Online
OpenStudy (anonymous):

Help!!

OpenStudy (anonymous):

OpenStudy (dumbcow):

Law of cosines \[c^{2} = a^{2}+b^{2}-2ab \cos \theta\] where theta is always included angle opposite of side c

OpenStudy (anonymous):

yea but i m getting a negative answer..

OpenStudy (anonymous):

like...\[c ^{2}=(3)^{2}+(2\sqrt{2})^{2}-2(3)(2\sqrt{2})(3\lambda/4)\]

OpenStudy (anonymous):

c^2=9+8-39.98 c=N/A

OpenStudy (dumbcow):

check your cos(theta)....if theta > 90 then it will be neg

OpenStudy (anonymous):

ohh okay..

OpenStudy (anonymous):

so its c^2=9+8+39.98 c^2=56.98 c=7.548 <-- correct?

OpenStudy (dumbcow):

no the 39.98 is way too big

OpenStudy (dumbcow):

remember c< a+b --> c < 5.83

OpenStudy (anonymous):

hmmm...

OpenStudy (dumbcow):

did you take cos(3pi/4) ? looks like you just plugged in 3pi/4

OpenStudy (anonymous):

i got that answer..!! :)

OpenStudy (anonymous):

so its like \[c ^{2}=3^{2}+2\sqrt{2})^{2}-2(3)(2\sqrt{2})(-\sqrt{2}/2)\]

OpenStudy (anonymous):

c^2=9+8+12 c=5.385165

OpenStudy (dumbcow):

that looks better

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