Q 1 :

Let a variable line of slope m > 0 passing through the point (4, –9) intersect the coordinate axes at the points A and B. The minimum value of the sum of the distances of A and B from the origin is          [2024]

  • 10

     

  • 25

     

  • 30

     

  • 15

     

(2)

Equation of line passing through (4, –9) and having slope m is given by

(y + 9) = m(x – 4)

Since it intersect the coordinate axes at points A and B so at A, y = 0

   A = (9 + 4mm, 0)

Similarly at B, x = 0

   B = (0,  4m  9)

Now, let O(0, 0) be origin, then

OA + OB = (9 + 4mm)2 + (9 + 4m)2

= 9 + 4mm + 9 + 4m          [  m > 0]

= 13 + 9m + 4m

Now, 9m + 4m2  9m·4m          [  A.M.  G.M.]

   9m + 4m  12

   OA + OB  13 + 12  i.e.  25



Q 2 :

If the locus of the point, whose distance from the point (2, 1) and (1, 3) are in the ratio 5 : 4, is ax2+by2+cxy+dx+ey+170=0, then the value of a2+2b+3c+4d+e is equal to :          [2024]

  • 5

     

  • – 27

     

  • 37

     

  • 437

     

(3)

Let given point be (h, k) whose distance from (2, 1) and (1, 3) is in ratio 5 : 4.

   (h - 2)2 + (k - 1)2(h - 1)2 + (k - 3)2 = 2516

   h2 + k2 - 4h - 2k + 5h2 + k2 - 2h - 6k + 10 = 2516

On replacing h by x and k by y, we get

16x2 + 16y2 - 64x - 32y + 80 = 25x2 + 25y2 - 50x - 150y + 250

   9x2 + 9y2 + 14x - 118y + 170 = 0

On comparing, we get

a = 9, b = 9, c = 0, d = 14, e = -118

   a2 + 2b + 3c + 4d + e = 81 + 18 + 56 - 118 = 37



Q 3 :

If the line segment joining the points (5, 2) and (2, a) subtends an angle π4 at the origin, then the absolute value of the product of all possible values of a is:          [2024]

  • 8

     

  • 2

     

  • 4

     

  • 6

     

(3)

m1 = 25, m2 = a2

Angle between the lines is π/4

Since, tan θ = |m1 - m21 + m1m2|

tan π4 = |25 - a21 + 25 × a2|   |25 -a  21 + a5|= 1

   |4 - 5a10 + 2a|= 1        4 - 5a10 + 2a = ±1

   4 - 5a10 + 2a = 1    or    4 - 5a10 + 2a = -1

   4 - 5a = 10 + 2a    or    4 - 5a = - 10 - 2a

   a = - 67    or    a = 143

   Required product = |- 67 × 143|= 4.



Q 4 :

A ray of light coming from the point P(1, 2) gets reflected from the point Q on the x-axis and then passes through the point R(4, 3). If the point S(h, k) is such that PQRS is a parallelogram, then hk2 is equal to:          [2024]

  • 70

     

  • 90

     

  • 60

     

  • 80

     

(1)

Slope of P'R = 3 - (-2)4 - 1 = 53

Equation of P'R : y + 2 = 53 (x - 1)

Since, point Q is on x-axis.

Let Q  (a, 0)

Also, point Q lies P'R

   65 = a - 1    a = 115

Now, PQRS is a parallelogram

   h + a2 = 4 + 12  h = 5 - 115 = 145

and 2 + 32 = k2  k = 5

   hk2 = 145 × 25 = 70



Q 5 :

Two vertices of a triangle ABC are A(3, –1) and B(–2, 3) and its orthocentre is P(1, 1). If the coordinates of the point C are (α,β) and the centre of the circle circumscribing the triangle PAB is (h, k), then the value of (α+β)+2(h+k) equals          [2024]

  • 15

     

  • 5

     

  • 51

     

  • 81

     

(2)

Slope of AB = -1 - 33 + 2 = -45

Slope of PE = 54

Equation of PC is given y - 1 = 54 (x - 1)

   4y – 4 = 5x – 5

   5x – 4y – 1 = 0         ... (i)

Now slope of AP = -1 - 13 - 1 = -1

Slope of BC = 1

Equation of BC is given by

y – 3 = 1(x + 2)

   xy + 5 = 0         ... (ii)

Solving (i) and (ii), we get

β = y = 26             [  C is point of intersection of PC and BC]

and α = x = 21

Centre of circle circumseribing PAB is point of intersection of perpendicular bisector of AP, AB and AC.

Equation of perpendicular bisector of AP

(y - (-1 + 1)2) = 1(x - (3 + 1)2)

  y – 0 = x – 2

  y = x – 2         ... (iii)

Equation of perpendicular bisector of AB

y - (3 - 12) = 54 (x - (-2 + 32))

   y - 1 = 54 (x - 12)        ... (iv)

On solving (iii) and (iv), we get

x = h = -192  and  y = k= -232

   2(h + k) = -42

So, (α+β) + 2(h + k) = 47 - 42 = 5.



Q 6 :

Let α,β,γ, δZ and let A(α,β),B(1,0),C(γ,δ) and D(1, 2) be the vertices of a parallelogram ABCD. If AB=10 and the points A and C lie on the line 3y = 2x + 1, then 2(α+β+γ+δ) is equal to          [2024]

  • 12

     

  • 10

     

  • 8

     

  • 5

     

(3)

Givem, A(α, β), B(1, 0), C(γ, δ) and D(1, 2).

Using mid point Formula.

α + γ=2

β + δ = 2

So, α + β + γ + δ = 2 + 2

α + β + γ + δ = 4

   2(α + β + γ + δ) = 2(4) = 8.



Q 7 :

Let A(2,1),B(1,0),C(α,β) and D(γ,δ) be the vertices of a parallelogram ABCD. If the point C lies on 2xy = 5 and the point D lies on 3x – 2y = 6, then the value of |α+β+γ+δ| is equal to __________.           [2024]



(32)

We have, A(–2, –1), B(1, 0), C(α, β) and D(γ, δ) be the vertices of a parallelogram ABCD.

Since, C(α, β) lies on 2xy = 5

   2α - β = 5          ... (i)

Also, D(γ, δ) lies on the line 3x – 2y = 6

So, 3γ - 2δ = 6          ... (ii)

Now, γ + 12 = α - 22  and  δ + 02 = β - 12

γ + 1 = α - 2  and  δ = β - 1

γ = α - 3          ... (iii)

From (ii), 3(α - 3) - 2(β - 1) = 6

Solving (i) and (iii), we get

α = -3; β = -11; γ = -6; δ = -12

   |α + β + γ + δ| = |-3 - 11 - 6 - 12| = 32.



Q 8 :

Let the three sides of a triangle are on the lines 4x – 7y + 10 = 0, x + y = 5 and 7x + 4y = 15. Then the distance of its orthocentre from the orthocentre of the triangle formed by the lines x = 0, y = 0 and x + y = 1 is          [2025]

  • 5

     

  • 20

     

  • 5

     

  • 20

     

(1)

Since the lines 4x –7y + 10 = 0 and 7x + 4y = 15 are perpendicular to each other.

So, the triangle formed by lines 4x –7y + 10 = 0, 7x + 4y = 15 and x + y = 5 is right angled triangle.

So, orthrocentre = Point of intersection of 4x – 7y + 10 = 0 and 7x + 4y = 15 which is, B = (1, 2)

Also, triangle formed by sides x = 0, y = 0, x + y = 1 is right angled triangle.

So, orthrocentre, Q = (0, 0)

   Distance between Q and B=1+4=5 units..



Q 9 :

Let the area of a PQR with vertices P(5, 4), Q(–2, 4) and R(a, b) be 35 square units. If its orthocenter and centroid are O(2,145) and C(c, d) respectively, then c + 2d is equal to          [2025]

  • 2

     

  • 3

     

  • 73

     

  • 83

     

(2)

Since, PRQT

  b4a5×6/54=1  b4a5×310=1

 10a3b=38          ... (i)

Also, PSQR

  6/53×b4a+2=1

 5a+2b=2          ... (ii)

Solving equations (i) and (ii), we get

a = 2, b = - 6

Now, centroid of PQR = (c, d)

 (52+23,4+463)=(c,d)

 c=53, d=23

  c+2d=53+43=3.



Q 10 :

Let the points (112,α) lie on or inside the triangle with sides x + y = 11, x + 2y = 16 and 2x + 3y = 29. Then the product of the smallest and the largest values of α is equal to :          [2025]

  • 22

     

  • 55

     

  • 33

     

  • 44

     

(3)

Given that a triangle bounded by lines L1: x + y = 11, L2: x + 2y =16 and L3: 2x + 3y = 29.

The region is given by

Using L1: When x=112, y = 11 – x

 α=11112=112     (minimum)

Using L3: when x = 11/2, 3y = 29 – 2x

 3α=292×112  3α=18

 α=6     (maximum)

   Product of the smallest and the largest value of α=112×6=33.



Q 11 :

Let Cr1n=28Crn=56 and Cr+1n=70. Let A(4 cos t, 4 sin t), B(2 sin t, – 2 cos t) and C(3rn, r2n – 1) be the vertices of a triangle ABC, where t is a parameter. If (3x1)2+(3y)2=α, is the locus of the centroid of triangle ABC, then α equals         [2025]

  • 18

     

  • 8

     

  • 20

     

  • 6

     

(3)

We have, Cr1n=28Crn=56 and Cr+1n=70

Cr1nCrn=2856  n!(r1)!(nr+1)!×r!(nr)!n!=12

 r(nr+1)=12  3r=n+1          ... (i)

Also, CrnCr+1n=5670  r+1nr=45  9r=4n5         ... (ii)

From equations (i) and (ii), we get r = 3 and n = 8.

Now, A = (4 cos t, 4 sin t), B(2 sin t, – 2 cos t) and C(1, 0)

   Centroid of triangle is

               (4cost+2sint+13,4sint2cost3)

Then, (3x1)2+(3y)2=(4cost+2sint)2+(4sint 2cost)2(3x1)2+(3y)2=20

So, value of α=20.



Q 12 :

Let A(4, –2), B(1, 1) and C(9, –3) be the vertices of a triangle ABC. Then the maximum area of the parallelogram AFDE, formed with vertices D, E and F on the sides BC, CA and AB of the triangle ABC respectively, is __________..         [2025]



(3)

The maximum area of a parallelogram inscribed in a triangle is half the area of the triangle.

Now, Area of ABC=12|4(1(3))+1(3(2))+9(21)|

                                             =12|16127|=6 sq. units

   Area of parallelogram AFDE = 3 sq. units.



Q 13 :

Let A(6, 8), B(10 cos α, – 10 sin α) and C(–10 sin α, 10 cos α), be the vertices of a triangle. If L(a, 9) and G(h, k) be its orthocenter and centroid respectively, then (5a – 3h + 6k + 100 sin 2α) is equal to __________.          [2025]



(145)

We can observe that all the three points A, B, C lie on the circle x2+y2=100, so circumcentre is (0, 0). Since, centroid divides the line joining orthocentre and circumcentre in the ratio 2 : 1, then

a+03=h  a=3h

and 9+03=k  k=3

Also, 6+10cosα10sinα3=h

 10(cosαsinα)=3h6          ... (i)

and 8+10cosα10sinα3=k          

 10(cosαsinα)=3k8=98=1             ... (ii)

On squaring, 100 (1 – sin 2α) = 1  100 sin 2α = 99

From (i) and (ii), we get h=73

Now, 5a – 3h + 6k +100 sin 2α

= 15h – 3h + 6k + 100 sin 2α12×73+18+99 = 145.



Q 14 :

Let G(α,β) be the circumcentre of the triangle formed by the lines 4x+3y=69,4y-3x=17 and x+7y=61. Then (α-β)2+α+β is equal to      [2023]

  • 16

     

  • 17

     

  • 18

     

  • 15

     

(2)

Let ABC be a triangle with

AB:4x+3y=69  (i)

BC:4y-3x=17  (ii)

AC:x+7y=61  (iii)

Solving (i) and (ii), we get   B(9,11)

Solving (ii) and (iii), we get  C(5,8)

Solving (i) and (iii), we get  A(12,7)

Now,  AG2=GB2

(12-α)2+(7-β)2=(9-α)2+(11-β)2

 8β-6α=9    ...(iv)

Similarly, GC2=GB2

 (5-α)2+(8-β)2=(9-α)2+(11-β)2

8α+6β=113  (v)

Now solving (iv) and (v), we get  

        α=172, β=152

   (α-β)2+α+β=17



Q 15 :

Let R be the rectangle given by the lines x=0,x=2,y=0 and y=5. Let A(α,0) and B(0,β),α[0,2] and β[0,5], be such that the line segment AB divides the area of the rectangle R in the ratio 4 : 1. Then, the midpoint of AB lies on a         [2023]

  • parabola

     

  • hyperbola

     

  • straight line

     

  • circle

     

(2)

ar(APQRB)ar(OAB)=41

Let M be the mid-point of AB.

M(h,k)(α2,β2)

10-12αβ12αβ=4   52αβ=10

  αβ=4

  (2h)(2k)=4

  Locus of M is xy=1, which is a hyperbola.



Q 16 :

If the point (α,733) lies on the curve traced by the mid-points of the line segments of the lines xcosθ+ysinθ=7,θ(0,π2) between the coordinate axes, then α is equal to            [2023]

  • - 7

     

  • -73

     

  • 73

     

  • 7

     

(4)

Given line is xcosθ+ysinθ=7

x-intercept=7cosθ, y-intercept=7sinθ

Let locus of intercept be (h,k).

(h,k)=(72cosθ, 72sinθ)

h=72cosθ, k=72sinθ

α=72cosθ, 733=72sinθ

cosθ=72α, sinθ=32

cos2θ+sin2θ=1

494α2+34=1 494α2=14

     α2=49

   α=7      (As θ(0,π2))



Q 17 :

Let A(1, 2) and C(−3, −6) be two diagonally opposite vertices of a rhombus, whose sides AD and BC are parallel to the line 7xy=14 If B (α,β) and D(γ,δ) are the other two vertices, then |α+β+γ+δ| is equal to.   [2026]

  • 6

     

  • 1

     

  • 3

     

  • 9

     

(1)

Given the points of B and D are (α,β) and (γ,δ) and midpoint of A and C is (-1,-2)

So α+γ2=-1  and  β+δ2=-2

|α+γ+β+δ|=6



Q 18 :

Among the statements

(S1): If A(5,−1) and B(−2,3) are two vertices of a triangle, whose orthocentre is (0,0), then its third vertex is (−4,−7).

(S2): If positive numbers 2a,b,c are three consecutive terms of an A.P., then the lines ax+by+c=0 are concurrent at (2,−2).     [2026]

  • both are correct

     

  • both are incorrect

     

  • only (S2) is correct

     

  • only (S1) is correct

     

(1)

Solution of statement-1

mAO·mBC=-1

B(-2,3)

5h-k+13=0    ...(1)

&  mAB·mOC=-1

4k=7h    ...(2)

third vertex is (-4,-7)

 Statement 1 is correct.

Solution of statement-2

2a,b,cA.P.

b=2a+c2

2a-2b+c=0

 lines ax+by+c=0 are concurrent then

x2=y-2=11

x=2  and  y=-2

 Point of concurrency is (2,-2)

 Statement 2 is correct.



Q 19 :

Let ABC be an equilateral triangle with orthocenter at the origin and the side BC on the line x+22y=4 If the co-ordinates of the vertex A are (α,β) then the greatest integer less than or equal to |α+2β| is.     [2026]

  • 2

     

  • 5

     

  • 4

     

  • 3

     

(3)

  mBC·mAD=-1

(-122)(βα)=-1

β=22α  ...(1)

 OD=|-41+8|=43AO=83

So AD=83+43=4

|α+22β-4|3=4α=169 or -89

{A(α,β) & (0,0) lie on same side of given line}

 (α,β)=(169,3229) (Rejected)

so (α,β)=(-89,-1629)

=[|α+2β|]=[|-8-329|]=4