in a triangle,R=2r then the triangle is
a)right angle
b)isosceles
c)equilateral
d)none
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2 Answers
1r=4Rsin\left(\frac{A}{2} \right)sin\left( \frac{B}{2}\right)sin\left(\frac{C}{2} \right)
putting r=2R we get RHS=1/8 which can be easily seen to be true for A=B=C=60 so option c is correct
341To give some context: Euler's inequality. http://en.wikipedia.org/wiki/Euler%27s_inequality
