The curve for which the normal at any point (x, y) and the line joining the origin to that point form an isosceles triangle with the x-axis as the base is
Let $z = e^{i\theta}$,
then $a = 1 + e^{i\theta} + e^{2i\theta} = \dfrac{\sin(3\theta/2)}{\sin(\theta/2)} e^{i\theta}$.
After simplification, the value $\dfrac{1}{3}$ is not possible.
Let $K$ be the set of all odd numbers less than $200$ and $M$ be the set of products of two distinct numbers taken from $K$, then find the total number which is divisible by $5$ in $M$.
Let numbers be $a, b$.
Then $\dfrac{x}{y} = \dfrac{\sqrt{ab}}{\dfrac{2ab}{a+b}} = \dfrac{a+b}{2\sqrt{ab}} = \dfrac{5}{4}$.
Let $\dfrac{a}{b} = r$,
then $\dfrac{r+1}{2\sqrt{r}} = \dfrac{5}{4}$.
On solving, $r = 4$ or $\dfrac{1}{4}$.
Hence ratio = $1:4$.
Sum of squares of first $n$ odd numbers $= \dfrac{n(2n-1)(2n+1)}{3}$.
For $n = 50$, sum $= \dfrac{50 \times 99 \times 101}{3} = 166650$.
Hence, it lies between $150000$ and $250000$.
Substitute $y = 4x + C$ in $x^2 + 4y^2 = 4$.
To touch, discriminant $= 0$.
After solving, $C = \pm \dfrac{2}{\sqrt{17}}$.
Hence, there are $2$ possible values.
In the triangle $ABC$, sides $AB$, $BC$, and $CA$ are extended such that $B'$, $C'$, and $A'$ are the new points formed.
If the area of $\triangle ABC = 1$ unit and
$AA' = 2AB,\ BB' = 2BC,\ CC' = 3AC$,
then find the area of $\triangle A'B'C'$.
The probability distribution function of a random variable $X$ is given by
$f(x) = \dfrac{x}{18}, ; 0 \le x \le 6$
$= 0, \text{ otherwise}$
Then the value of $P(X > 2)$ is
If, for a binomial distribution, the number of trials is $9$, the variance is $2$ and the probability of success is greater than that of failure, find the probability of both success.
Two customers, Rachana and Bhakti, are visiting a particular shop in the same week (Tuesday to Saturday). Each is equally likely to visit the shop on any day as on another day. What is the probability that both will visit the shop on consecutive days?
Total days = 5 (Tuesday to Saturday).
Total possible pairs $= 5 \times 5 = 25$.
Consecutive day pairs = $(T,W), (W,T), (W,Th), (Th,W), (Th,F), (F,Th), (F,S), (S,F)$ → total 8.
So, $P = \dfrac{8}{25}$.
Find the distance from the eye at which a coin of $2\ \text{cm}$ diameter should be held so as to conceal the full moon whose angular diameter is $31'$.
A company models the rate of change of concentration by
$(y^2+3xy),dx+(x^2+xy),dy=0$, with $y=1$ when $x=1$. Find $y$ as a function of $x$ (choose the correct option).
$\text{Coeff}{x^n},(1+x)^{2n}=\binom{2n}{n}$ and $\text{Coeff}{x^n},(1+x)^{2n-1}=\binom{2n-1}{n}$.
$\displaystyle \binom{2n}{n}=\frac{(2n)}{n,n}=\frac{2n}{n}\cdot\frac{(2n-1)}{n,(n-1)}=2\binom{2n-1}{n}$.
So ratio $=2:1$.
For $y^2=4x$, we need $x=\dfrac{y^2}{4}$.
For $y=\pm4$, $x=\dfrac{16}{4}=4$ $\Rightarrow$ $(4,4)$ and $(4,-4)$ satisfy.
Others give $x\neq\dfrac{y^2}{4}$.
$\sqrt{1+\cos 2x}=\sqrt{2},|\cos x|$. On $\left[\frac{\pi}{2},\pi\right]$, $\cos x\le 0$ so $|\cos x|=-\cos x$.
LHS $=\sqrt{2},|\cos x|$, RHS $=\sqrt{2},|\cos x|$ only if $\cos^{-1}(\cos x)=|\cos x|$, which never holds for $x\in\left[\frac{\pi}{2},\pi\right]$.
Hence no real solution.
Line passes through $A(6,7,7)$ with direction $\vec v=\langle3,2,-2\rangle$.
$\vec{AP}=\langle-5,-5,-4\rangle$. Distance $=\dfrac{\lVert \vec{AP}\times\vec v\rVert}{\lVert\vec v\rVert}=\dfrac{\sqrt{833}}{\sqrt{17}}=\sqrt{49}=7$.
Let $t=\tan\left(\dfrac{1}{2}\tan^{-1}x\right)=\dfrac{1-x}{1+x}$.
Using $\tan(2\theta)=\dfrac{2t}{1-t^2}=x$, we get $x=\dfrac{1-x^2}{2x}\Rightarrow 3x^2=1\Rightarrow x=\pm\dfrac{1}{\sqrt3}$.
From the equation, $x>0$.
Let AB be a chord of a circle $x^2+y^2 = r^2$ subtending a right angle at the centre. Then, the locus of the centroid of the triangle PAB as P moves on the circle is
If $A(cos\alpha, sin\alpha)$, $B(sin\alpha, -cos\alpha)$, C(1,2) are the vertices of a $\Delta ABC$, then as $\alpha$ varies, the the locus of its centroid is,
A right circular cone with radius R and height H contains a liquid which evaporates at a rate proportional to its surface area in contact with air (proportionally constant= k>0 ). Find the time after which the cone is empty.
Two numbers are selected randomly from a set S={1,2,3,4,5,6} without replacement one by one. The probability that minimum of the two numbers is less than 4 is :
The probability of a shooter hitting a target is $\frac{3}{4}$. How many minimum numbers of times must he/she fire so that the probability of hitting the target at least once is more than 0.99?
A line intersects lines 5x-y-4=0 and 3x-4y-4=0 at point A and B. If a point P(1, 5) on the line AB is such that AP: PB=2:1(internally), then point A is,
Straight lines are drawn by joining m points on a straight line to n points on another line. Then excluding the given points, the number of point of intersection of the lines drawn is (no two lines drawn are parallel and no three lines are concurrent).