Quantitative Aptitude Ques 1272
Question: Evaluate $ \frac{1-{{\tan }^{2}}30{}^\circ }{1+\tan 30{}^\circ }. $
Options:
A) 1/2
B) 2
C) 1/3
D) 3
Show Answer
Answer:
Correct Answer: A
Solution:
- Given expression, $ \frac{1-{{\tan }^{2}}30{}^\circ }{1+{{\tan }^{2}}30{}^\circ } $
$ =\frac{1-{{( \frac{1}{\sqrt{3}} )}^{2}}}{1+{{( \frac{1}{\sqrt{3}} )}^{2}}} $ $ [ \because \tan 30{}^\circ =\frac{1}{\sqrt{3}} ] $
$ =\frac{1-\frac{1}{3}}{1+\frac{1}{3}}=\frac{2/3}{4/3}=\frac{2}{3}\times \frac{3}{4}=\frac{1}{2} $