Trigonometric Equations Question 274
Question: In $ \Delta ,ABC $ , $ a=2cm,b=3cm $ and $ c=4cm $ , then angle A is
[MNR 1973; MP PET 1984, 2002]
Options:
A) $ {{\cos }^{-1}}( \frac{1}{24} ) $
B) $ {{\cos }^{-1}}( \frac{11}{16} ) $
C) $ {{\cos }^{-1}}( \frac{7}{8} ) $
D) $ {{\cos }^{-1}}( -\frac{1}{4} ) $
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Answer:
Correct Answer: B
Solution:
- Use $ \cos A=\frac{b^{2}+c^{2}-a^{2}}{2bc} $ .
BETA
