Question:

Let A(α, -2), B(α, 6) and C(\(\frac{\alpha}{4}\), -2) be vertices of a ΔABC. If (5, \(\frac{\alpha}{4}\)) is the circumcentre of ΔABC, then which of the following is NOT correct about ΔABC?

Updated On: Sep 13, 2024
  • Area is 24
  • Perimeter is 25
  • Circumradius is 5
  • Inradius is 2
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The Correct Option is B

Solution and Explanation

Circumcentre of ΔABC
=(\(\alpha+\frac{\frac{\alpha}{4}}{2}\),\(\frac{6-2}{2}\))
=(\(\frac{5\alpha}{8}\), 2)
=(5,\(\frac{\alpha}{4}\))
⇒α=8
Area (ΔABC)=\(\frac{1}{2}\)⋅3α4×8=24 sq. units
Perimeter =8+\(\frac{3\alpha}{4}\)+\(\sqrt{82}\)+(\(\frac{3\alpha}{4}^2\))
=8+6+10=24
Circumradius=\(\frac{10}{2}\)=5
r=\(\frac{\Delta}{s}\)
r=\(\frac{24}{12}\)
r=2
So, the correct option is (B): Perimeter is 25.
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