Friday, October 23, 2015

`tan(x + pi) + 2sin(x + pi) = 0` Find all solutions of the equation in the interval [0, 2pi).

`tan(x+pi)+2sin(x+pi)=0 , 0<=x<=2pi`


using `tan(x+pi)=tan(x) , sin(x+pi)=-sin(x)`


`tan(x)-2sin(x)=0`


`sin(x)/cos(x)-2sin(x)=0`


`sin(x)-2sin(x)cos(x)=0`


`sin(x)(1-2cos(x))=0`


solving each part separately,


`sin(x)=0 , (1-2cos(x))=0`


For sin(x)=0,


General solutions are,


`x=0+2pin , x=pi+2pin`


solutions for the range `0<=x<=2pi`  are,


`x=0,pi,2pi` 


solving`1-2cos(x)=0`


`cos(x)=1/2`


General solutions for cos(x)=1/2 are,


`x=pi/3+2pin, (5pi)/3+2pin`


Solutions for the range `0<=x<=2pi`  are,


`x=pi/3 , (5pi)/3`


combine all the solutions,


`x=0,pi,2pi,pi/3,(5pi)/3`

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