JEE Main 2022 · 29 Jul · Shift 2 · Mathematics Q13

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MathematicsSingle correct+4 / -1Question 13 of 90

Let A(α, −2), B(α, 6) and C $\left(\dfrac\alpha4,-2\right)$ be vertices of a ΔABC. If $\left(5,\dfrac\alpha4\right)$ is the circumcentre of ΔABC, then which of the following is NOT correct about ΔABC ?

area is 24

perimeter is 25

circumradius is 5

inradius is 2

Answer and worked solution

Official answer: B

Find α. The perpendicular bisector of AB is $y=2$ , so $\frac\alpha4=2$ , $\alpha=8$ : A(8, −2), B(8, 6), C(2, −2).

Right angle at A with legs 8 and 6, hypotenuse 10: area 24, perimeter 24, R = 5, r = 2. "Perimeter 25" is wrong.

(B)

Topics:Distance and section formulae Properties of triangles

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JEE Main 2022 · 29 Jul · Shift 2, Mathematics question 13