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Student Support Forum: 'Error solving a Cos[x]^2 + b Sin[x]^2 + c Sin[x] Cos[x] == 0' topicStudent Support Forum > General > "Error solving a Cos[x]^2 + b Sin[x]^2 + c Sin[x] Cos[x] == 0"

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Author Comment/Response
Edward Boas
 10/18/99 04:31am

I'm getting an incorrect solution when solving:

a Cos[x]^2 + b Sin[x]^2 + c Sin[x] Cos[x] == 0

for x. Any ideas on what's going on?

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Here's what I'm doing:

f[x_] := a Cos[x]^2 + b Sin[x]^2 + c Sin[x] Cos[x]
FullSimplify[Solve[f[x] == 0, x]]

FullSimplify[f[ (copy and paste solution from output above) ]]
The output of this last expression is not 0!

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Subject (listing for 'Error solving a Cos[x]^2 + b Sin[x]^2 + c Sin[x] Cos[x] == 0')
Author Date Posted
Error solving a Cos[x]^2 + b Sin[x]^2 + c Sin[... Edward Boas 10/18/99 04:31am
Re: Error solving a Cos[x]^2 + b Sin[x]^2 + c ... randy silvers 10/27/99 8:16pm
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