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Elementary Mathematics
Loci and concurrency
If C is a circle passing through three non-collinear points D,E, F such that DE = EF = DF = 3 cms, then radius of the circle C is
A) \( \Large \frac{\sqrt{3}}{2}\ cm \)
B) \( \Large \sqrt{3}\ cm \)
C) \( \Large \frac{1}{\sqrt{3}}\ cm \)
D) \( \Large \frac{2}{\sqrt{3}}\ cm \)
Correct Answer:
B) \( \Large \sqrt{3}\ cm \)
Description for Correct answer:
\( \Large FM = \sqrt{ \left(3\right)^{2}- \left(\frac{3}{2}\right)^{2} } = \sqrt{9-\frac{9}{4}} = \frac{\sqrt{27}}{2} \)
Now FO : OM = 2 : 1
\( \Large \therefore\ \frac{\sqrt{27}}{2}=2x+1x \)
\( \Large \frac{3\sqrt{3}}{2}=3x \)
\( \Large \therefore\ x = \frac{\sqrt{3}}{2} \)
\( \Large \therefore\ FO = 2x = 2 \times \frac{\sqrt{3}}{2} \)
=> \( \Large FO = \sqrt{3} = r \)
Therefore, Hene radius of circle is \( \Large \sqrt{3}\ cm \)
Part of solved Loci and concurrency questions and answers :
>> Elementary Mathematics
>> Loci and concurrency
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