JEE MAIN - Mathematics (2016 - 9th April Morning Slot - No. 10)
A circle passes through (−2, 4) and touches the y-axis at (0, 2). Which one of the following equations can represent a diameter of this circle?
4x + 5y − 6 = 0
2x − 3y + 10 = 0
3x + 4y − 3 = 0
5x + 2y + 4 = 0
Explanation
_9th_April_Morning_Slot_en_10_1.png)
EF = perpendicular bisector of chord AB
BG = perpendicular to y-axis
Here C = center of the circle
mid-point of chord AB, D = ($$-$$ 1, 3)
slope of AB = $${{4 - 2} \over { - 2 - 0}}$$ = $$-$$ 1
$$ \because $$ EF $$ \bot $$ AB
$$ \therefore $$ Slope of EF = 1
Equation of EF, y $$-$$ 3 = 1 (x + 1)
$$ \Rightarrow $$ y = x + 4 . . . .(i)
Equation of BG
y = 2 . . . . (ii)
From equations (i) and (ii)
x = $$-$$ 2, y = 2
since C be the point of intersection of EF and BG, therefore center, C = ($$-$$ 2, 2)
Now coordinates of center C satiesfy the equation
2x $$-$$ 3y + 10 = 0
Hence 2x $$-$$ 3y + 10 = 0 is the equation of the diameter
Comments (0)
