| sin(x+y) |
| cos(x+y) |
| sin(x−y) |
| cos(x−y) |
=
| sin[(x+y)+(x−y)] |
| cos2x•cos2y−sin2x•sin2y |
=
| sin2x |
| cos2x−(cos2x+sin2x)sin2y |
=
| sin2x |
| cos2x−sin2y |
| sin2x |
| cos2x−sin2y |
| sin(x+y) |
| cos(x+y) |
| sin(x−y) |
| cos(x−y) |
| sin[(x+y)+(x−y)] |
| cos2x•cos2y−sin2x•sin2y |
| sin2x |
| cos2x−(cos2x+sin2x)sin2y |
| sin2x |
| cos2x−sin2y |