`sin(2x)-sin(x)=0 , 0<=x<=2pi`
using the identity `sin(2x)=2sin(x)cos(x)`
`sin(2x)-sin(x)=0`
`=2sin(x)cos(x)-sin(x)=0`
`=(sin(x))(2cos(x)-1)=0`
solving each part separately,
`sin(x)=0` or `2cos(x)-1=0`
General solutions for sin(x)=0 are,
`x=0+2(pi)n, x=pi+2(pi)n`
solutions for the range `0<=x<=2pi` are,
`x=0 , x=pi , x=2pi`
Now solving 2cos(x)-1=0,
`2cos(x)=1`
`cos(x)=1/2`
General solutions for cos(x)=1/2 are,
`x=(pi)/3+2pin , x=(5pi)/3+2pin`
solutions for the range `0<=x<=2pi` are,
`x=pi/3 , x=(5pi)/3`
Hence all the solutions are,
`x=0,pi,2pi,pi/3 , (5pi)/3`
No comments:
Post a Comment