^{4}θ + sec

^{4}θ

^{4}θ/ cos

^{4}θ ) + (1/ cos

^{ 4}θ) as tan θ = Sin θ / Cosθ and Sec θ = 1/Cos θ

^{4}θ -Sin

^{4}θ +1 ) / Cos

^{4}θ as Cos

^{4 }θ - Sin

^{4}θ = (Cos

^{2}θ -Sin

^{2}θ ) ( Cos

^{ 2}θ + Sin

^{2}θ) =(Cos

^{2}θ -Sin

^{2}θ )

^{2}θ - Sin

^{2}θ +1)/( Cos

^{4}θ )

^{2}θ/ Cos

^{4}θ = 2/Cos

^{2}θ =2 Sec

^{2}θ

Mark M.

02/09/17