Quantitative Aptitude Ques 386
Question: If $ \sin \theta =\frac{a}{\sqrt{a^{2}+b^{2}}}, $ then the value of cot 6 will be
Options:
A) $ \frac{b}{a} $
B) $ \frac{a}{b} $
C) $ \frac{a}{b}+1 $
D) $ \frac{b}{a}+1 $
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Answer:
Correct Answer: A
Solution:
- Given, $ \sin \theta =\frac{a}{\sqrt{a^{2}+b^{2}}} $
(i)
We know that, $ \sin \theta =\frac{Perpendicular}{Hypotenuse} $
Now, $ \Delta ABC, $ $ \sin \theta =\frac{AB}{AC} $
.(ii)
On comparing Eqs. (i) and (ii) we get
$ AB=a $ and $ AC=\sqrt{a^{2}+b^{2}} $
Now in $ \Delta ABC, $ by Pythagoras theorem,
$ AB^{2}+BC^{2}=AC^{2} $
$ BC^{2}=b^{2} $
$ \Rightarrow $ $ BC=b $
$ \Rightarrow $ $ \cot \theta =\frac{b}{a} $