Mathematics

Question

Solve the equation: Sin2x - Sinx = 0

1 Answer

  • We know that sin2x=2sinxcosx 
    (search the net for proof if you wish) 

    So the original equation becomes

    2sinxcosx-sinx=0
    The two terms both have sinx that can be taken out to get: 

    sinx(2cosx-1)=0 
    This is true if sinx=0 or 2cosx-1=0 , rewritten: cosx=1/2

    sinx=0 than x=2kπ
    cosx=1/2 than x=π/3+2kπ
    where k is an integer