Q43 / 90 · JEE Main 2022 (29 Jul Shift 2) · Mathematics

Let Aα,-2,Bα,6 and Cα4,-2 be vertices of a ∆ABC. If 5,α4 is the circumcentre of ∆ABC, then which of the following is NOT correct about ∆ABC

  • A
    ares is 24
  • Correct answer
    B
    perimeter is 25
  • C
    circumradius is 5
  • D
    inradius is 2

Solution

Given,

Aα,-2, Bα,6 & Cα4,-2

Now slope of AC=0 and slope of AB=80→∞

Now we can see AC is perpendicular to AB.

So, ∆ABC is right angled at A.

So, Circumcentre =mid point of BC=5α8,2

Now given circumcentre ≡5,α4

So on comparing we get,5α8=5 & α4=2

⇒α=8

Now plotting the diagram and finding the sides with distance formula we get,

Figure

Area =1268=24

Perimeter =24

Circumradius =102=5

Inradius =Δs=2412=2

Hence, the correct answer is option: 'B'.

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