Trigonometric Equations Question 237
Question: In $ \Delta ABC $ , $ a^{2}({{\cos }^{2}}B-{{\cos }^{2}}C)+ $ $ b^{2}({{\cos }^{2}}C-{{\cos }^{2}}A)+ $ $ c^{2}({{\cos }^{2}}A-{{\cos }^{2}}B)= $
Options:
A) 0
B) 1
C) $ a^{2}+b^{2}+c^{2} $
D) $ 2(a^{2}+b^{2}+c^{2}) $
Show Answer
Answer:
Correct Answer: A
Solution:
- $ \Sigma a^{2}({{\cos }^{2}}B-{{\cos }^{2}}C)=\Sigma a^{2}({{\sin }^{2}}C-{{\sin }^{2}}B) $ $ =k^{2}\Sigma a^{2}(c^{2}-b^{2})=0 $ .
BETA
