Question

100 points...
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1)complete
sin (a+b)=?
sin (a-b)=?
cos (a+b)=?
cos (a-b)=?

2)complete
sinc + sind=?
sinc - sind=?
cosc + cosd=?
cosc - cosd=?

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Answer 1

Step-by-step explanation:

1) sin(a+b)=sinacosb +cosasinb

sin(a-b) = sinacosb -cosasinb

cos(a+b) = cosacosb - sinasinb

cos(a-b) = cosacosb +sinasinb

2) sinc + sind = 2 sin[c+d/2].cos[c-d/2]

sinc - sind = 2sin[c-d/2].cos[c+d/2]

cosc+cosd = 2 cos[c+d/2].cos[c-d/2]

cosc - cosd = -2sin[c+d/2].sin[c-d/2]

Answer 2

Refer to attachment.

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