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Demonstreaza ca:
1.
[tex] \sin(a + b) = \sin(a) \times \cos(b) + \sin(b) \times \cos(a) [/tex]
2.
[tex] \sin(a + b) = \sin(a) \cos(b) - \sin(b) \times \cos(a) [/tex]
cu explicatie va roog