Cos (a-b) - cos (a+b) = 2 sin a sin b

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Mathematics

Cesar

13 January, 14:35

Cos (a-b) - cos (a+b) = 2 sin a sin b

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Monique Mccarty · Answer 1

cos (a - b) - cos (a + b) = 2sin (a) sin (b)

[cos (a) cos (b) + sin (a) sin (b) ] - [cos (a) cos (b) - sin (a) sin (b) ] = 2sin (a) sin (b)

[cos (a) cos (b) - cos (a) cos (b) ] + [sin (a) sin (b) + sin (a) sin (b) ] = 2sin (a) sin (b)

2sin (a) sin (b) = 2sin (a) sin (b)