Ans the question quickly

Dear Student,
$$\begin{gathered} 2.Cose{c}^{2}67°-{\tan }^{2}23° \\ =Cose{c}^{2}67°-{\tan }^2\left(90°-67°\right) \\ =Cose{c}^{2}67°-Co{t}^{2}67° \\ =1 \end{gathered}$$
kindly ask different questions in different posts.
Regards