Trigonometryhard · Past Paper
If sin A + sin B = x and cos A + cos B = y, then tan((A+B)/2) is:
Ax/y
By/x
Cx+y
Dxy
✓ Correct Answer: A — x/y
Dividing (2 sin((A+B)/2) cos((A-B)/2)) by (2 cos((A+B)/2) cos((A-B)/2)) gives tan((A+B)/2) = x/y.
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