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9.Straight Line
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A pair of straight lines $x^2 - 8x + 12 = 0$ and $y^2 - 14y + 45 = 0$ are forming a square. Co-ordinates of the centre of the circle inscribed in the square are
A
$(3, 6)$
B
$(4, 7)$
C
$(4, 8)$
D
none
Solution
$\quad x^{2}-8 x+12=0$
$\Rightarrow(x-6)(x-2)=0$
$y^{2}-14 y+45=0$
$(y-5)(y-9)=0$
Thes sides of square are
x=2, x=6, y=5, y=9
The centre of circle in square will be
$\left(\frac{2+6}{2}, \frac{5+9}{2}\right)=\left(\frac{8}{2}, \frac{14}{2}\right)$
$=(4,7)$
Standard 11
Mathematics