f: \(\Leftrightarrow\dfrac{1-cos2x}{2}+\dfrac{3}{2}sin2x=1\)
=>3/2sin2x-1/2cos2x=1/2
=>3 sin2x-cos2x=1
\(\Leftrightarrow sin2x\cdot\dfrac{3}{\sqrt{10}}-cos2x\cdot\dfrac{1}{\sqrt{10}}=\dfrac{1}{\sqrt{10}}\)
=>\(sin\left(2x-a\right)=sina\)(với cos a=3/căn 10)
=>2x-a=a+k2pi hoặc 2x-a=pi-a+k2pi
=>2x=2a+k2pi hoặc 2x=pi+k2pi
=>x=a+kpi hoặc x=pi/2+kpi