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Maths Help (1 Viewer)

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3sinx = cosx

How do I solve this equation?I know it may seem easy but I forgot. Please help me thank you :)
 

Trebla

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Moved to Maths Ext1 thread.

For future reference, please post these questions in the Maths forum.
 

pikachu975

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3sinx = cosx

How do I solve this equation?I know it may seem easy but I forgot. Please help me thank you :)
Minus cosx to both sides, so sqrt3 sinx - cosx = 0
cosx (sqrt3 tanx - 1) = 0
cosx = 0 and tanx = 1/sqrt3
cosx = 0 isn't valid since tan(pi/2) doesn't exist so only tanx = 1/sqrt3 is a solution
x = pi/6 then the other solutions depend on the domain of x

In this case dividing by cosx on both sides would give the right answer but in other questions it might remove a solution so be careful
 

idkkdi

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Minus cosx to both sides, so sqrt3 sinx - cosx = 0
cosx (sqrt3 tanx - 1) = 0
cosx = 0 and tanx = 1/sqrt3
cosx = 0 isn't valid since tan(pi/2) doesn't exist so only tanx = 1/sqrt3 is a solution
x = pi/6 then the other solutions depend on the domain of x

In this case dividing by cosx on both sides would give the right answer but in other questions it might remove a solution so be careful
ye check scenario where the thing u divide by = 0 , in case that is a possible solution.
 

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