The general solution to sin10x+cos10x=2916cos42x is
sin10x+cos10x=2916cos42x
or, (1−cos2x2)5+(1+cos2x2)5=2916cos42x
Let cos 2x=t
then (1−t2)5+(1+t2)5=2916t4
or, 24t4−10t2−1=0
or, (2t2−1)(12t2+1)=0
or, 12t2+1≠0
∴so,2t2−1=0 then t2=12
Put the value of t
so, cos22x=12 or,2cos22x−1=0
or, cos4x=0
or, 4x=nπ+π2 or, x=nπ4+π8,n∈I