Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Advanced 2018Paper 2
Exam
JEE Advanced
Year
2018
Paper
Paper 2
Subject
Mathematics
Chapter
Circle

JEE Advanced 2018 · Paper 2 · Mathematics · Circle

Let T be the line passing through the points P(- 2, 7) and Q (2, -...

Let TT be the line passing through the points P(−2,7)andQ(2,−5).LetP\left(- 2, 7\right) and Q \left(2, - 5\right). Let{F}_{1}be the setofallpairsofcircles(S1,S2)suchthatset of all pairs of circles \left({S}_{1}, {S}_{2}\right) such thatTistangentstois tangents to{S}_{1}atatP and tangent to S2{S}_{2} at QQ, and also such that S1andS2{S}_{1} and {S}_{2} touch each other at a point, say, MM. Let E1{E}_{1} be the set representing the locus of MastheMas thepair \left({S}_{1}, {S}_{2}\right) varies inF1{F}_{1}. Let the set of all straight line segments joining a pair of distinct points of E1{E}_{1} and passing through the point R(1,1)R\left(1,1\right) be F2{F}_{2} . Let E2{E}_{2} be the set of the mid-points of the line segments in the set F2{F}_{2} . Then, which of the following statement(s) is (are) TRUE?Let T be the line passing through the points P(- 2, 7) and Q (2, - 5). Let F _ 1 be the set of all pairs of circles ( SLet T be the line passing through the points P(- 2, 7) and Q (2, - 5). Let F _ 1 be the set of all pairs of circles ( S

Options

  1. AThe point (−2,7)\left(- 2,7\right) lies in E1{E}_{1}
  2. BThe point (45,75)\left(\dfrac{4}{5}, \dfrac{7}{5}\right) does NOT lie in E2{E}_{2}
  3. CThe point (12,1)\left(\dfrac{1}{2}, 1\right) lies in E2{E}_{2}
  4. DThe point (0,32)\left(0, \dfrac{3}{2}\right) does NOT lie in E1{E}_{1}

Correct answer

B. The point (45,75)\left(\dfrac{4}{5}, \dfrac{7}{5}\right) does NOT lie in E2{E}_{2}

Step-by-step solution

Let T be the line passing through the points P(- 2, 7) and Q (2, - 5). Let F _ 1 be the set of all pairs of circles ( S

AP=AQ=AMAP = AQ = AM So ∠PMQ=90°∠ PMQ = 90 °
Locus of MM is a circle having PQPQ as its diameter
Hence, E1:x2+y2−2y−39=0,x≠±2{E}_{1}: {x}^{2} + {y}^{2} - 2y - 39 = 0, x \ne \pm 2
Clearly \left(- 2, 7\right)isnotincludedinthelocusbecausewecannotconsiderpointcircles,and (0,32)is not included in the locus because we can not consider point circles, and \left(0, \dfrac{3}{2}\right) does not lie on E1{E}_{1} as it does not satisfy the equation above.
Let T be the line passing through the points P(- 2, 7) and Q (2, - 5). Let F _ 1 be the set of all pairs of circles ( S
The equation of chord with B(h,k) asmidpointwillbegivenbyB\left(h, k\right) as mid point will be given byT = {S}_{1}or</p><p>or</p><p>xh + yk - y - k - 39 = {h}^{2} + {k}^{2} - 2k - 39</p><p>or</p><p>orxh + yk - y + k = {h}^{2} + {k}^{2}</p><p>Itpassesthrough</p><p>It passes throughR\left(1, 1\right).So,</p><p>. So,</p><p>h + k - 1 + k = {h}^{2} + {k}^{2}</p><p>orthelocusof</p><p>or the locus of{E}_{2}isis{x}^{2} + {y}^{2} - x - 2y + 1 = 0</p><p>Butif</p><p>But ifPisnotthepartoflocusofis not the part of locus ofMthenthenPQisnotthechordoflocusofis not the chord of locus ofM.Sopoint (45,75). So point \left(\dfrac{4}{5}, \dfrac{7}{5}\right) does not lie in E2{E}_{2}. \left(\dfrac{1}{2}, 1\right)doesnotsatisfytheequationhencedoesnotlieindoes not satisfy the equation hence does not lie in{E}_{2}.

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 Advanced PYQs