- #1
songoku
- 2,336
- 337
- 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