=30 ⇒‌‌y2−30y+81=0 ⇒‌‌(y−27)(y−3)=0 ⇒‌‌y=3 or y=27 81sin2x=3 or 81sin2x=27 34sin2x=3 or 34sin2x=33 ⇒‌‌4sin2x=1 or 4sin2x=3 ⇒‌‌sin2x=1/4 or sin2x=3∕4 ⇒‌‌sin2x=sin2(π/6) or sin2x=sin2(π/3) ⇒‌‌x=nπ±π/6 or x=nπ±π/3 From [0,π], x=π/6,5π/6 or x=π/3,2π/3 Hence, the total number of solutions =4