Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main 202131 AugustEvening Shift
Exam
JEE Main
Year
2021
Date
31 August
Shift
Evening Shift
Subject
Mathematics
Chapter
Circle

JEE Main 2021 · 31 August · Evening Shift · Mathematics · Circle

Let B be the centre of the circle x ^ 2 + y ^ 2 - 2x + 4y + 1 = 0 ....

Let BB be the centre of the circle x2+y2−2x+4y+1=0.{x}^{2} + {y}^{2} - 2x + 4y + 1 = 0 . Let the tangents at two points PandP andQonthecircleintersectatthepointon the circle intersect at the pointA ( 3, 1 ) .ThenThen8(areaδAPQareaδBPQ)\left(\dfrac{area\delta APQ}{area\delta BPQ}\right) is equal to .Let B be the centre of the circle x ^ 2 + y ^ 2 - 2x + 4y + 1 = 0 . Let the tangents at two points P and Q on the

Correct answer

0

Step-by-step solution

Given, centre of circle x2+y2−2x+4y+1=0.....(i){x}^{2} + {y}^{2} - 2x + 4y + 1 = 0 . . . . . \left(i\right)

Points B(1,−2) and A(3,1)B\left(1, - 2\right) \text{ and } A\left(3, 1\right)

For point P,y=−2P, y = - 2

Putting value of yy in equation \left(i\right)</p><p></p><p>{x}^{2} + {\left(- 2\right)}^{2} - 2x + 4 \times \left(- 2\right) + 1 = 0</p><p></p><p>{x}^{2} - 2x - 3 = 0</p><p>(x−3)(x+1)=0</p><p>\left(x - 3\right)\left(x + 1\right) = 0

x=−1x = - 1 (not possible)

x=3x = 3

Point P(3,−2)P\left(3, - 2\right)

AP=(3−3)2+(−2−1)2AP = \sqrt{{\left(3 - 3\right)}^{2} + {\left(- 2 - 1\right)}^{2}}

AP=3=AQAP = 3 = AQ

r=(1)2+(−2)2−1r = \sqrt{{\left(1\right)}^{2} + {\left(- 2\right)}^{2} - 1}

r=1+4−1r = \sqrt{1 + 4 - 1}

r=2r = 2
tanθ=32tan\theta = \dfrac{3}{2}

Area(δAPQ)Area(δBPQ)=ARRB\dfrac{Area ( \delta APQ )}{Area ( \delta BPQ )} = \dfrac{AR}{RB}

=3sinθ2cosθ=94= \dfrac{3sin\theta}{2cos\theta} = \dfrac{9}{4}

8(Area(δAPQ)Area(δBPQ))=188\left(\dfrac{Area ( \delta APQ )}{Area ( \delta BPQ )}\right) = 18
Let B be the centre of the circle x ^ 2 + y ^ 2 - 2x + 4y + 1 = 0 . Let the tangents at two points P and Q on the

Practice Circle on Quantrex Academy →

More from Circle

Match each entry in List-I to the correct entry in List-II and choose the correct option.… JEE Advanced 2026Consider the circle C: x^2+y^2-6x-8y-11=0 . Let a variable chord AB of the circle C… JEE Main 2026Let C be a circle having centre in the first quadrant and touching the x -axis at a… JEE Main 2026Let the line x - y = 4 intersect the circle C: (x-4)^2 + (y+3)^2 = 9 at the points Q and… JEE Main 2026Let the centre of the circle x^2 + y^2 + 2gx + 2fy + 25 = 0 be in the first quadrant and… JEE Main 2026Let P be a moving point on the circle x^2 + y^2 - 6x - 8y + 21 = 0 . Then, the maximum… JEE Main 2026Suppose that two chords, drawn from the point (1, 2) on the circle x^2 + y^2 + x - 3y = 0… JEE Main 2026Let a circle pass through the origin and its centre be the point of intersection of two… JEE Main 2026Let a circle C have its centre in the first quadrant, intersect the coordinate axes at… JEE Main 2026Let the circle x^ 2 +y^ 2 =4 intersect x -axis at the points A(a, 0), a>0 and B(b, 0) .… JEE Main 2026Let y=x be the equation of a chord of the circle C_ 1 (in the closed half-plane x ≥ 0 )… JEE Main 2026Let S=\ z ∈ ℂ:|(z-6 i)/(z-2 i)|=1. and .|(z-8+2 i)/(z+2 i)|=(3)/(5)\ . Then ∑_ z ∈ ~s… JEE Main 2026Let a circle of radius 4 pass through the origin O, the points A(- 3 a, 0) and B(0,- 2 b)… JEE Main 2026If the points of intersection of the ellipses x^ 2 +2 y^ 2 -6 x-12 y+23=0 and 4 x^ 2 +2… JEE Main 2026Let the set of all values of r , for which the circles (x+1)^ 2 +(y+4)^ 2 =r^ 2 and x^ 2… JEE Main 2026If P is a point on the circle x^ 2 +y^ 2 =4, Q is a point on the straight line 5 x+y+2=0… JEE Main 2026 Full Circle list Circle JEE Maths PYQsJEE Mathematics PYQs All JEE Main PYQs