The number of solutions of (sin2x+cos2x)1+sin4x=2 in [−π,π] is equal to
(sin2x+cos2x)(sin2x+cos2x)2=2⇒sin2x+cos2x=2⇒sin2x+π4=1⇒2x+π4=2nπ+π2⇒x=nπ+π8
for, x∈[−π,π], put n=−1,0,1
we get, x=−7π8,π8