Trig Sum to Product Identities

[Dinomite07]

I know how to find Product to Sum Identities with Sum and Difference Identites.
But how do you find Sum to Product Identities?

 

[Deleted member 4993]

I know how to find Product to Sum Identities with Sum and Difference Identities.
But how do you find Sum to Product Identities?

Can you give us an example (Product to Sum Identities with Sum and Difference Identities)?

Can you give us an example of the problem (Sum to Product Identities)?

 

[Dinomite07]

Can you give us an example (Product to Sum Identities with Sum and Difference Identities)?

Can you give us an example of the problem (Sum to Product Identities)?

Product to Sum Identities with Sum and Difference Identities Example

cos(A + B) = cos A cos B - sin A sin B
cos(A - B) = cos A cos B + sin A sin B
___________________________________________

cos(A + B) + cos(A - B) = 2 cos A cos B

cos A cos B = 0.5[cos(A + B) + cos(A - B)]


The problem is that I don't know how Sum to Product Identities are derived from Sum and Difference Identities.

 

[Dinomite07]

Can you give us an example (Product to Sum Identities with Sum and Difference Identities)?

Can you give us an example of the problem (Sum to Product Identities)?

Product to Sum Identities with Sum and Difference Identities


cos(A + B) = cos A cos B - sin A sin B
cos(A - B) = cos A cos B + sin A sin B
_____________________________________________________

cos(A + B) + cos(A - B) = 2 cos A cos B

cos A cos B = 0.5[cos(A + B) + cos(A - B)]


The problem is I don't know how Sum to Product Identities are derived from Sum and Difference Identities.