If (4 sin θ + 5 cos θ ) = 3 , then the value of (4 cos θ -5 sin θ ) is :
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Correct answer: B
Explanation
The correct answer is option 2 i.e. 4 .
a sinθ + b cosθ = c
a cosθ − b sinθ = d
a2 + b2 = c2 + d2
4 sinθ + 5 cosθ = 3
Let 4 cosθ − 5 sinθ = x
⇒ 42 + 52 = 32 + x2
⇒ x = = = 4