- #1

songoku

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- Homework Statement
- Given that sin A + sin B = 1 and cos A + cos B = 0, find the value of 12 cos 2A + 4 cos 2B

- Relevant Equations
- Trigonometry

Let:

equation 1 : sin A + sin B = 1

equation 2 : cos A + cos B = 0

Squaring both sides of equation 1 and 2 then add the result gives me: cos (A - B) = -1/2

Then how to proceed? Thanks

equation 1 : sin A + sin B = 1

equation 2 : cos A + cos B = 0

Squaring both sides of equation 1 and 2 then add the result gives me: cos (A - B) = -1/2

Then how to proceed? Thanks