Trigonometric Equations Question 77
Question: In $ \Delta ABC,\ \frac{1}{a}{{\cos }^{2}}\frac{A}{2}+\frac{1}{b}{{\cos }^{2}}\frac{B}{2}+\frac{1}{c}{{\cos }^{2}}\frac{C}{2}= $
Options:
A) $ s $
B) $ \frac{s}{abc} $
C) $ \frac{s^{2}}{abc} $
D) $ \frac{s^{3}}{abc} $
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Answer:
Correct Answer: C
Solution:
- $ \frac{1}{a}{{\cos }^{2}}\frac{A}{2}+\frac{1}{b}{{\cos }^{2}}\frac{B}{2}+\frac{1}{c}{{\cos }^{2}}\frac{C}{2} $ = $ \sum \frac{s(s-a)}{abc}=\frac{s(s-a+s-b+s-c)}{abc}=\frac{s^{2}}{abc} $ .
BETA
