Trigonometric Equations Question 139
Question: In an equilateral triangle the inradius and the circum-radius are connected by
[EAMCET 1983]
Options:
A) $ r=4R $
B) $ r=R/2 $
C) $ r=R/3 $
D) None of these
Show Answer
Answer:
Correct Answer: B
Solution:
- $ r=4R\sin \frac{A}{2}\sin \frac{B}{2}\sin \frac{C}{2} $
$ \Rightarrow $ $ r=4R{{\sin }^{3}}30^{o} $ , $ {\because A=B=C=60^{o}} $
$ \Rightarrow $ $ r=\frac{R}{2} $ .
BETA
