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Question

 If 3 sin θ + 5 cos θ = 5, then what is the value of 5 sin θ – 3 cos θ equal to ?

  1. 5
  2. -3
  3. -2
  4. 0
Answer

Given, 3 sin θ + 5 cos θ = 5   –i)

Let,     5 sin θ – 3 cos θ =x     –ii) 

Squaring and adding (i) and (ii) we get,

=>$$34(sin^2θ+cos^2θ)=25+x^2$$

=> $$34=25+x^2$$

=> x = ±3,

Hence from the option we get -3

Answer – (B)