i really do not noe what ans u expect becoz trigo questions of this type are generally to prove...well let me give u astart it it can help

take tan^2 common in last two terms and then use 1+tan^2=sec^2 to get

tan^6 + tan^2(sec^2)

now take tan^2 common again and again use the above formula to get

tan^2( (sec^2 - 1)^2 +sec^2)

to get

tan^2(sec^4 +1- sec^2)