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JEE Main 202329 JanuaryMorning Shift
Exam
JEE Main
Year
2023
Date
29 January
Shift
Morning Shift
Subject
Mathematics
Chapter
Straight Lines

JEE Main 2023 · 29 January · Morning Shift · Mathematics · Straight Lines

Let B and C be the two points on the line y + x =0 such that B and...

Let BB and CC be the two points on the line y+x=0y + x =0 such that BB and CC are symmetric with respect to the origin. Suppose AA is a point on y−2x=2y - 2x = 2 such that ∆ABC∆ ABC is an equilateral triangle. Then, the area of the ∆ABC∆ ABC isLet B and C be the two points on the line y + x =0 such that B and C are symmetric with respect to the origin. Suppose

Options

  1. A333\sqrt{3}
  2. B232\sqrt{3}
  3. C83\dfrac{8}{\sqrt{3}}
  4. D103\dfrac{10}{\sqrt{3}}

Correct answer

C. 83\dfrac{8}{\sqrt{3}}

Step-by-step solution

On plotting the diagram of the given data we get,

Let B and C be the two points on the line y + x =0 such that B and C are symmetric with respect to the origin. Suppose

Now given, x=yx = y and y−2x=2y - 2x = 2

On solving we get, A(−2,−2)A ( - 2, - 2 )

Now height hh of ∆ABC∆ ABC = Distance of point AA to origin,

h=(−2)2+(−2)2h = \sqrt{{\left(- 2\right)}^{2} + ( - 2{)}^{2}}

⇒h=22⇒ h = 2\sqrt{2}

Given ∆ABC∆ ABC is an equilateral triangle,

So, sin⁡(B)=hAB\sin \left(B\right) = \dfrac{h}{AB}

⇒sin⁡(60°)=hAB(∵∠A=∠B=∠C=60°)⇒ \sin \left({60}^{°}\right) = \dfrac{h}{AB} ( ∵ ∠ A = ∠ B = ∠ C = {60}^{° )}

Area of Δ=34(AB)2\Delta = \dfrac{\sqrt{3}}{4}{\left(AB\right)}^{2}

⇒⇒Area of Δ=34h2sin⁡260∘=34×323\Delta = \dfrac{\sqrt{3}}{4}\dfrac{{h}^{2}}{\sin^{2}{60}^{∘}} = \dfrac{\sqrt{3}}{4} \times \dfrac{32}{3}

So, Area of ∆ABC=83∆ ABC = \dfrac{8}{\sqrt{3}}

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