If a cos θ - b sin θ = c, then a sin θ + b cos θ is: – Trigonometry

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.

Share this question