Trigonometryhard · Past Paper
If a cos θ - b sin θ = c, then a sin θ + b cos θ is:
Asqrt(a²+b²-c²)
Bsqrt(a²+b²+c²)
Ca+b-c
Dsqrt(c²-a²-b²)
✓ Correct Answer: A — sqrt(a²+b²-c²)
Let x = a sin + b cos. Square both equations and add: (a cos - b sin)² + (a sin + b cos)² = c² + x². a² + b² = c² + x².
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