Qus : 1
MCA NIMCET PYQ
1
If the circles
$ x^2 + y^2 + 2x + 2ky + 6 = 0$
and
$x^2 + y^2 + 2ky + k = 0$
intersect orthogonally, then $k$ is:
1
$2 \text{ or } -\dfrac{3}{2}$ 2
$-2 \text{ or } -\dfrac{3}{2}$ 3
$2 \text{ or } \dfrac{3}{2}$ 4
$-2 \text{ or } \dfrac{3}{2}$ Go to Discussion
MCA NIMCET Previous Year PYQ
MCA NIMCET NIMCET 2012 PYQ
Solution
Two circles:
$C_1:\; x^2 + y^2 + 2x + 2ky + 6 = 0$
$C_2:\; x^2 + y^2 + 2ky + k = 0$
Orthogonality condition for circles
$x^2 + y^2 + 2g_1 x + 2f_1 y + c_1 = 0$
and
$x^2 + y^2 + 2g_2 x + 2f_2 y + c_2 = 0$
is:
$2(g_1g_2 + f_1f_2) = c_1 + c_2$
From $C_1$:
$g_1 = 1,\; f_1 = k,\; c_1 = 6$
From $C_2$:
$g_2 = 0,\; f_2 = k,\; c_2 = k$
Apply formula:
$2(1\cdot 0 + k\cdot k) = 6 + k$
$2k^2 = 6 + k$
$2k^2 - k - 6 = 0$
$(2k + 3)(k - 2) = 0$
So:
$k = 2 \;\text{or}\; -\dfrac{3}{2}$
Qus : 2
MCA NIMCET PYQ
4
Number of distinct solutions of
$ x^{2} = y^{2} $
and
$ (x - a)^{2} + y^{2} = 1 $
where $a$ is any real number:
1
$0,1,2,3,4$ 2
$0,1,3$ 3
$0,1,2$ 4
$0,2,3,4$ Go to Discussion
MCA NIMCET Previous Year PYQ
MCA NIMCET NIMCET 2011 PYQ
Solution $ x^{2} = y^{2} \Rightarrow x = \pm y $
Intersection with a circle shifted by $a$ gives variable counts depending on $a$.
Possible solution counts: $0,1,2,4$
Qus : 11
MCA NIMCET PYQ
4
The circle $x^2 + y^2 = 9$ is contained in the circle $x^2 + y^2 - 6x - 8y + 25 = c^2$ if
1
$c = 2$ 2
$c = 3$ 3
$c = 5$ 4
$c = 10$ Go to Discussion
MCA NIMCET Previous Year PYQ
MCA NIMCET NIMCET 2010 PYQ
Solution Given circle 1: center (0,0), radius 3
Circle 2 (rewrite): (x-3)² + (y-4)² = c²
Distance between centers = √(3² + 4²) = 5
Condition: larger radius ≥ smaller radius + distance
c ≥ 3 + 5 = 8
Given options → smallest suitable c is 10
Qus : 13
MCA NIMCET PYQ
4
A circle with its center in the first quadrant touches both the coordinate axes and the line
x-y-2=0. Then the area of the circle is
1
$\dfrac{\pi}{2}$ 2
$4 \pi$ 3
$\pi$ 4
$2\pi$ Go to Discussion
MCA NIMCET Previous Year PYQ
MCA NIMCET NIMCET 2025 PYQ
Solution A circle touching both coordinate axes has center $(r, r)$ and radius $r$.
It also touches the line $x - y - 2 = 0$.
So the distance from $(r, r)$ to the line equals $r$:
$\dfrac{|r - r - 2|}{\sqrt{1^{2} + (-1)^{2}}} = r$
$\dfrac{2}{\sqrt{2}} = r$
$r = \sqrt{2}$
Area of the circle:
$\pi r^{2} = \pi(\sqrt{2})^{2} = 2\pi$
Qus : 14
MCA NIMCET PYQ
3
The circle $x^2 + y^2+ \alpha x+ \beta y+ \gamma=0$ is the image of the circle $x^2 + y^2- 6x- 10y+ 30=0$ across
the line 3x + y = 2. The value of $[\alpha+ \beta+ \gamma]$ is (where [.] represents the floor function.)
1
20 2
22 3
23 4
21 Go to Discussion
MCA NIMCET Previous Year PYQ
MCA NIMCET NIMCET 2025 PYQ
Solution Given circle:
$x^{2}+y^{2}-6x-10y+30=0$
Center and radius:
$C(3,5), \quad r=2$
We reflect $C(3,5)$ across the line
$3x + y - 2 = 0$.
Compute reflection factor:
$k = \dfrac{2(3\cdot 3 + 5 - 2)}{3^{2} + 1^{2}}
= \dfrac{24}{10}
= \dfrac{12}{5}$
Reflected center:
$x' = 3 - 3k = 3 - \dfrac{36}{5} = -\dfrac{21}{5}$
$y' = 5 - k = 5 - \dfrac{12}{5} = \dfrac{13}{5}$
So new center is:
$C'\left(-\dfrac{21}{5},\dfrac{13}{5}\right)$
The image circle is
$x^{2}+y^{2}+\alpha x+\beta y+\gamma = 0$
Using center formula:
$-\dfrac{\alpha}{2} = -\dfrac{21}{5} \Rightarrow \alpha = \dfrac{42}{5}$
$-\dfrac{\beta}{2} = \dfrac{13}{5} \Rightarrow \beta = -\dfrac{26}{5}$
Using radius $r=2$:
$\left(-\dfrac{21}{5}\right)^{2} + \left(\dfrac{13}{5}\right)^{2} - \gamma = 4$
$\dfrac{610}{25} - \gamma = 4$
$\gamma = \dfrac{102}{5}$
Now compute:
$\alpha + \beta + \gamma
= \dfrac{42}{5} - \dfrac{26}{5} + \dfrac{102}{5}
= \dfrac{118}{5}
= 23.6$
Thus,
$\boxed{23}$
Qus : 19
MCA NIMCET PYQ
3
There are n equally spaced points 1,2,...,n marked on the circumference of a circle. If the point 15 is directly opposite to the point 49, then the total number of points is
1
50 2
68 3
66 4
70 Go to Discussion
MCA NIMCET Previous Year PYQ
MCA NIMCET NIMCET 2016 PYQ
Solution Given: $n$ equally spaced points $1, 2, \ldots, n$ marked on circumference of a circle
Point $15$ is directly opposite to point $49$
Since the points are equally spaced on a circle, two points are directly opposite if they are diametrically opposite
$\therefore$ The number of points between $15$ and $49$ on each semicircle must be equal
Points between $15$ and $49$ (going from $15$ to $49$):
$16, 17, 18, \ldots, 48$
Number of points $= 48 - 16 + 1 = 33$
Since both semicircles must have equal number of points between the opposite points:
Points on other semicircle (from $49$ to $15$) must also be $33$
$\therefore$ Total number of points $= 2 + 33 + 33 = 68$
Qus : 21
MCA NIMCET PYQ
2
. Two common tangents to the circles $x^2 + y^2 = 2a^2$ and parabola $y^2 = 8ax$ are
1
$x = \pm (y + 2a)$ 2
$y = \pm (x + 2a)$ 3
$x = \pm (y + a)$
4
$y = \pm (x + a)$ Go to Discussion
MCA NIMCET Previous Year PYQ
MCA NIMCET NIMCET 2016 PYQ
Solution Given circle: $x^2 + y^2 = 2a^2$
Given parabola: $y^2 = 8ax$
**Equation of tangent to parabola:**
For parabola $y^2 = 8ax$, tangent is:
$y = mx + \dfrac{2a}{m}$ ...(i)
**Condition for tangent to circle:**
For line $y = mx + \dfrac{2a}{m}$ to be tangent to circle $x^2 + y^2 = 2a^2$,
distance from centre $(0,0)$ = radius $= \sqrt{2}\ a$
$\Rightarrow \dfrac{\left|\dfrac{2a}{m}\right|}{\sqrt{1 + m^2}} = \sqrt{2}\ a$
$\Rightarrow \dfrac{2a}{|m|\sqrt{1+m^2}} = \sqrt{2}\ a$
$\Rightarrow \dfrac{2}{|m|\sqrt{1+m^2}} = \sqrt{2}$
$\Rightarrow |m|\sqrt{1+m^2} = \sqrt{2}$
Squaring both sides:
$\Rightarrow m^2(1+m^2) = 2$
$\Rightarrow m^4 + m^2 - 2 = 0$
$\Rightarrow (m^2 + 2)(m^2 - 1) = 0$
$\Rightarrow m^2 = 1 \quad (\because m^2 = -2 \text{ is not possible})$
$\Rightarrow m = \pm 1$
**Substituting in (i):**
When $m = 1$: $y = x + 2a$
When $m = -1$: $y = -x - 2a$
$\therefore$ The two common tangents are:
$\therefore \boxed{y = x + 2a \quad \text{and} \quad y = -(x + 2a)}$
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