Evaluate sec2 d - JAMB Mathematics 2009 Question

∫sec²θ dθ = ∫ 1/cos² dθ

∫(cos)^-2 dθ,

let u = cos θ

∴∫u^-2 = ¹/_u + c

∫cos θ = sin θ + c

∫sec^-2θ = ¹/_u sin θ + c

= (sinθ / cosθ) + c

= Tan θ + c