Y = sec θ tan θ differentiate

Y = sec (θ) tan (θ).

Solution:

We use here the product rule that is

(fg) 0 = f 0 g + fg0.

So

y 0 = (sec (θ) tan (θ)) tan (θ) + sec (θ) tan2 (θ)

= sec (θ) (tan2 (θ) + sec2 (θ)).