Answer:
Only the second equation is an identity
Step-by-step explanation:
1)
[tex]1+\dfrac{\cos^2\theta}{\cot^2\theta(1-\sin^2\theta)}= \\\\\\1+\dfrac{\cos^2\theta}{\cot^2\theta(\cos^2\theta)}= \\\\\\1+\dfrac{1}{\cot^2 \theta}= \\\\\\1+\tan^2\theta=\sec^2\theta\neq 2\sec^2 \theta[/tex]
This one is not an identity.
2)
[tex]19\cos \theta\left( \dfrac{1}{\cos \theta}-\dfrac{\tan \theta}{\csc \theta} \right)= \\\\\\19\cos \theta \left( \dfrac{1}{\cos \theta}-\dfrac{\sin^2 \theta}{\cos \theta} \right)= \\\\\\19\cos \theta \left( \dfrac{1-\sin^2 \theta}{\cos \theta}\right)= \\\\\\19\cos \theta \left( \dfrac{\cos^2 \theta}{\cos \theta}\right)= \\\\\\19\cos \theta (\cos \theta)= \\\\\\19\cos^2 \theta = 19\cos^2 \theta[/tex]
This one is an identity. Therefore, only the second equation is an identity. Hope this helps!
