Quantitative Aptitude Ques 1269

Question: If $ (\cos \theta +\sec \theta )=2, $ then $ ({{\cos }^{2}}\theta +{{\sec }^{2}}\theta ) $ is equal to

Options:

A) $ \frac{1}{2} $

B) 2

C) 4

D) $ \frac{1}{4} $

Show Answer

Answer:

Correct Answer: B

Solution:

  • $ \cos \theta +\sec \theta =2 $ $ {{(\cos \theta +\sec \theta )}^{2}}={{(2)}^{2}} $ [squaring on both sides] $ {{\cos }^{2}}\theta +{{\sec }^{2}}\theta +2\cos \theta \times \sec \theta =4 $

$ \Rightarrow $ $ {{\cos }^{2}}\theta +{{\sec }^{2}}\theta +2=4 $

$ \Rightarrow $ $ {{\cos }^{2}}\theta +{{\sec }^{2}}\theta =4-2 $

$ \Rightarrow $ $ {{\cos }^{2}}\theta +{{\sec }^{2}}\theta =2 $