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Given a triangle with a=11, b=14, and α=15°, what is (are) the possible length(s) of c?

 Dec 8, 2015

Best Answer 

 #1
avatar+26396 
+10

Given a triangle with a=11, b=14, and α=15, what is (are) the possible length(s) of c?

 

a2=b2+c22bccos(α)c22bcos(α)c+b2a2=0 Ac2+Bc+C=0c=B±B24AC2A c22bcos(α)c+b2a2=0A=1B=2bcos(α)C=b2a2c=2bcos(α)±(2bcos(α))24(b2a2)2c=bcos(α)±[bcos(α)]2(b2a2)c=bcos(α)±b2[cos2(α)1]+a2c=bcos(α)±b2[1sin2(α)1]+a2c=bcos(α)±a2b2sin2(α)a=11b=14α=15c=14cos(15)±112142sin2(15)c=140.96592582629±107.870489571c=13.5229615680±10.3860719028c1=13.5229615680+10.3860719028c1=23.9090334709c2=13.522961568010.3860719028c2=3.13688966521

 

 

check:

c1c2=(ba)(ba+2a)c1c2=(ba)(b+a)c1c2=b2a2a=11b=14c1c2=142112c1c2=75c1c2=23.90903347093.13688966521c1c2=75 Okay

 

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 Dec 9, 2015
 #1
avatar+26396 
+10
Best Answer

Given a triangle with a=11, b=14, and α=15, what is (are) the possible length(s) of c?

 

a2=b2+c22bccos(α)c22bcos(α)c+b2a2=0 Ac2+Bc+C=0c=B±B24AC2A c22bcos(α)c+b2a2=0A=1B=2bcos(α)C=b2a2c=2bcos(α)±(2bcos(α))24(b2a2)2c=bcos(α)±[bcos(α)]2(b2a2)c=bcos(α)±b2[cos2(α)1]+a2c=bcos(α)±b2[1sin2(α)1]+a2c=bcos(α)±a2b2sin2(α)a=11b=14α=15c=14cos(15)±112142sin2(15)c=140.96592582629±107.870489571c=13.5229615680±10.3860719028c1=13.5229615680+10.3860719028c1=23.9090334709c2=13.522961568010.3860719028c2=3.13688966521

 

 

check:

c1c2=(ba)(ba+2a)c1c2=(ba)(b+a)c1c2=b2a2a=11b=14c1c2=142112c1c2=75c1c2=23.90903347093.13688966521c1c2=75 Okay

 

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heureka Dec 9, 2015

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