(81)sin2x+(81)cos2x=30
(81)sin2x+(81)sin2x(81)1=30
(81)sin2x=t
t+t81=30
t2−30t+81=0
(t−3)(t−27)=0
(81)sin2x=31 or (81)sin2x=33
34sin2x=31 or 34sin2x=33
sin2x=41 or sin2x=43
Hence, total 4 solution.
The number of roots of the equation, (81)sin2x+(81)cos2x=30 in the interval [0,π] is equal to :
Held on 16 Mar 2021 · Verified 6 Jul 2026.
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