tan2θ+cot2θ+2=
tan2θ+cosec2θ
sec2θ+cosec2θ
tan2θ+cot2θ+2
This can be re-written as
⇒1+tan2θ+1+cot2θ
⇒cosec2θ+sec2θ (∵1+tan2θ=cosec2θ and 1+cot2θ=sec2θ)
Hence tan2θ+cot2θ+2=sec2θ+cosec2θ