A) 2
B) 4
C) 3
D) 1
Correct Answer: A
Solution :
\[sin\text{ }x-sin\text{ }2x+sin\text{ }3x=0\] \[x\,\in \,\left[ 0,\,\,\frac{\pi }{2} \right)\] \[\Rightarrow \] \[\left( sin\,3\,x+sin\,x \right)-sin\,2x=0\] \[\Rightarrow \,\,\,\,2sin2x.cos2x-sin2x=0\] \[\Rightarrow \,\,\,\,\,sin2x\,\left( 2cosx-1 \right)=0\] \[sin\text{ }2x=0~~~~and\text{ }cos\text{ }x=\frac{1}{2}\] \[\text{x=0}\] \[\text{x=}\frac{\pi }{3}\] two solutionsYou need to login to perform this action.
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