Trigonometric Equations Question 280
Question: The smallest angle of the $ \Delta ABC $ , when $ a=7,b=4\sqrt{3} $ and $ c=\sqrt{13}, $ is
[MP PET 2003]
Options:
A) $ 30^{o} $
B) $ 15^{o} $
C) $ 45^{o} $
D) None of these
Show Answer
Answer:
Correct Answer: A
Solution:
- Smallest angle is opposite to smaller side.
$ \therefore \cos C=\frac{b^{2}+a^{2}-c^{2}}{2ab}=\frac{49+48-13}{2\times 7\times 4\sqrt{3}} $ $ =\frac{3}{2\sqrt{3}}=\frac{\sqrt{3}}{2} $
Þ $ \angle C=30^{o} $ .
BETA
