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Simplify the expression sin(45deg + A)*cos(45deg - B) + cos(45deg + A)*sin(45deg - B).

1. cos(A - B)
2. sin(A - B)
3. cos(A + B)
4. sin(A + B)

Correct answer: cos(A - B)

Solution

The expression matches sin(X+Y) with X = 45deg + A and Y = 45deg - B, giving sin(90deg + A - B) = cos(A - B).

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