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$A\ (3, 4)$ અને $B\ (5, -2)$ બે બિંદુઓ આપેલા છે. જો $PA = PB$ અને $\Delta PAB$ નું ક્ષેત્રફળ = $10$ હોય, તો $P$ શોધો.
$(7, 1)$
$(7, 2)$
$(-7, 2)$
$(-7, -1)$
Solution
Given that
$P A=P B$
area $\triangle P A B=10$ sq.unit
Let $p \equiv(x, y)$
$\therefore P A=P B$
$\Rightarrow PA ^2= PB ^2$
$\Rightarrow( x -3)^2+( y -4)^2=( x -5)^2+( y +2)^2$
$\Rightarrow x ^2-6 x +9+ y ^2-8 y +16= x ^2-10 x +25+ y ^2+4 y +4$
$\Rightarrow 4 x -12 y =4$
$\therefore x-3 y=1 \quad—(1)$
again
$\operatorname{area}(\triangle PAB )=10$
$\Rightarrow \frac{1}{2}\left| x _1\left( y _2- y _3\right)+ x _2\left( y _3- y _1\right)+ x _3\left( y _1- y _2\right)\right|=10$
$\Rightarrow| x (-2-4)+5(4- y )+3( y -(-2))|=20$
$\therefore 6 x-2 y+26=\pm 20$
From the question we get
$\Rightarrow-6 x -2 y +26=20 \quad \Rightarrow-6 x -2 y +26=-$
$\Rightarrow-6 x-2 y=-6 \quad \Rightarrow-6 x-2 y=-46$
$\Rightarrow 3 x + y =3–(2) \Rightarrow 3 x + y =23 \quad–(3)$
From equ" $(1)$ and $(2)$ we have
$x-3 t =1$
$3 x+y=3$
$\therefore x =1$ and $y =0$
from equan $(1)$ and $(3)$, we get
$x-3 y=1$
$3 x+y=23$
$\therefore x =7$ and $\therefore x =2$
$\therefore$ Required 00 – ordinate of point
$P$ are $(7,2)$