Trigonometric Identities Question 364

Question: $ (\sec 2A+1){{\sec }^{2}}A= $

Options:

A) $ \sec A $

B) $ 2\sec A $

C) $ \sec 2A $

D) $ 2\sec 2A $

Show Answer

Answer:

Correct Answer: D

Solution:

$ (\sec 2A+1){{\sec }^{2}}A=( \frac{1+{{\tan }^{2}}A}{1-{{\tan }^{2}}A}+1 ),(1+{{\tan }^{2}}A) $ $ =\frac{2,(1+{{\tan }^{2}}A)}{1-{{\tan }^{2}}A}=2\sec 2A. $