How do i prove sin3x=3sinx-4sinx?

Question

please hep!

Answer 1

As of my knowledge question was wrong, i think that question is sin(3x) = 3sin(x) - 4sin^3(x)

Left hand side identity

                                

Apply sum of angles formula

Apply double angle formulas

                 

From pythageron identitiey

               

             

             

               = Right hand side identity.