If (sin⁴ x)/2 + (cos⁴ x)/3 = 1/5, then
2sin4x+3cos4x=51
Find tan2x and 8sin8x+27cos8x
s=sin2x,c=cos2x
s+c=1
2s2+3c2=51
c=1−s
2s2+3(1−s)2=51
15s2+10(1−s)2=6
15s2+10−20s+10s2=6
25s2−20s+4=0
(5s−2)2=0 ⇒ 5s−2=0 ⇒ s=52
sin2x=52,cos2x=1−52=53
tan2x=cos2xsin2x=3/52/5=32
⇒option (1) is true, option (3) is false
8sin8x+27cos8x=8s4+27c4
s4=(52)4=62516,c4=(53)4=62581
816/625+2781/625=6252+6253=6255=1251
⇒option (2) is true, option (4) is false
Options (1) and (2) are correct
tan2x=32,8sin8x+27cos8x=1251