The given expression is, sin‌θ−3‌sin‌2‌θ+sin‌3‌θ=cos‌θ−3‌cos‌2‌θ+cos‌3‌θ The above expression can be expressed as, (2‌cos‌θ−3)(sin‌2‌θ−cos‌2‌θ)=0 If, (2‌cos‌θ−3)=0 cos‌θ=
3
2
The above expression is not valid. And, (sin‌2‌θ−cos‌2‌θ)=0 tan‌2‌θ=tan‌π‌4 θ=