Saved Bookmarks
| 1. |
Solve sin x-3 sin 2x + sin 3x = COS X - 3 cos 2x + cos3x |
|
Answer» sinx - 3sin2x + sin3x = cosx - 3cos2x + cos3xsinx + sin3x - 3sin2x = cosx + COS3X - 3cos2x2sin2xcosx - 3 sin2x - 2cos2x cosx + 3cos2x = 0sin2x(2COSX - 3) - cos2x(2cosx - 3) = 0(2cosx - 3)(sin2x - cos2x) = 0sin2x = cos2x as cos x ≠ 3/22x = 2n∏ ± (∏/2 - 2X) x = n∏/2 + ∏/8 |
|