Two sides of a parallelogram are along lines 4 x+5 y=0 and 7 x+2 y=0 . If equation of one of diagona

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9.Straight Line

hard

Two sides of a parallelogram are along the lines $4 x+5 y=0$ and $7 x+2 y=0$. If the equation of one of the diagonals of the parallelogram is $11 \mathrm{x}+7 \mathrm{y}=9$, then other diagonal passes through the point:

A$(1,3)$

B$(1,2)$

C$(2,2)$

D$(2,1)$

(JEE MAIN-2021)

Solution

Both the lines pass through origin.
point $D$ is equal of intersection of $4 x+5 y=0\, \,11 x+7 y=9$
So, coordinates of point $D=\left(\frac{5}{3},-\frac{4}{3}\right)$
Also, point $B$ is point of intersection of $7 x+2 y=0\, \, 11 x+7 y=9$
So, coordinates of point $B=\left(-\frac{2}{3}, \frac{7}{3}\right)$
diagonals of parallelogram intersect at middle let middle point of $B,D$
$\Rightarrow\left(\frac{\frac{5}{3}-\frac{2}{3}}{2}, \frac{-4}{3}+\frac{7}{3}\right)=\left(\frac{1}{2}, \frac{1}{2}\right)$
equation of diagonal $AC$
$\Rightarrow(y-0)=\frac{\frac{1}{2}-0}{\frac{1}{2}-0}(x-0)$
$y=x$
diagonal $AC$ passes through $(2,2)$

Standard 11

Mathematics

A line $L$ passes through the points $(1, 1)$ and $(2, 0)$ and another line $L'$ passes through $\left( {\frac{1}{2},0} \right)$ and perpendicular to $L$. Then the area of the triangle formed by the lines $L,L'$ and $y$- axis, is

medium

There are two candles of same length and same size. Both of them burn at uniform rate. The first one burns in $5\,hr$ and the second one burns in $3\,h$. Both the candles are lit together. After how many minutes the length of the first candle is $3$ times that of the other?

normal

(KVPY-2016)

Let the equations of two adjacent sides of a parallelogram $A B C D$ be $2 x-3 y=-23$ and $5 x+4 y$ $=23$. If the equation of its one diagonal $AC$ is $3 x +$ $7 y=23$ and the distance of A from the other diagonal is $d$, then $50 d ^2$ is equal to $……..$.

hard

(JEE MAIN-2023)

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normal

Let $PS$ be the median of the triangle with vertices $P(2,2) , Q(6,-1) $ and $R(7,3) $. The equation of the line passing through $(1,-1) $ and parallel to $PS $ is :