Question

solve the equation for for 0° ≤ x ≤ 360°
sin 2x - sin 3x + sin 4x = 0

Need help. Thanks!

Answer 1

use
sinA+sinB=2sin(A+B/2)sin(A-B/2)

Answer 2

that's wrong identity ^
sinA + sinB = 2 sin((A+B)/2)cos((A-B)/2)

Answer 3

first, simplify that
sin2x + sin4x
= 2sin((2x+4x)/2)cos((2x-4x)/2)
= 2sin(3x)cos(-x)
= 2sin3xcosx

Answer 4

so, sin 2x - sin 3x + sin 4x = 0
2sin3xcosx - sin3x = 0
factor out!
sin3x (2cosx - 1) = 0
set each factour equal zero then solve for x
sin3x = 0
x = .....

2cosx - 1 = 0
cosx = 1/2
x = .....

Answer 5

oh yes..i'm sorry! my mistake.

Answer 6

got it! thanks !!