this is the concept of trigonometry, to solve for the value of x we proceed as follows;
sin5x+sinx=sin3x
this can be written as:
(sinx)^5+sinx=(sinx)^3
dividing through by sin x we get:
(sinx)^4+1=(sinx)^2
let y=(sinx)^2
thus our expression will be given by:
y^2+1=y
y^2-y+1=0
solving the quadratic equation above we get:
y=(-1)^(1/3) or -(-1)^(2/3)
the above is a complex equation, therefore our expression has no defined answer