Trigonometric Equations Question 304
Question: If in triangle $ ABC,\cos A=\frac{\sin B}{2\sin C} $ , then the triangle is
[Orissa JEE 2002, 04; MP PET 2004]
Options:
A) Equilateral
B) Isosceles
C) Right angled
D) None of these
Show Answer
Answer:
Correct Answer: B
Solution:
- $ \cos A=\frac{\sin B}{2\sin C}\Rightarrow \frac{b^{2}+c^{2}-a^{2}}{2bc}=\frac{b}{2c} $
Þ $ b^{2}+c^{2}-a^{2}-b^{2}=0 $ Þ $ c^{2}=a^{2} $ .
BETA
