a straight line l intersects the circle 4x^2 +4y^2+18x-12y-2=0 at 2 points p and q.the slope of l is 3/4.if l passes through3,7,find the coordinates of p and q and the equation of the diameter which is perpendicular to l.do with full calculations
Question
a straight line l intersects the circle 4x^2 +4y^2+18x-12y-2=0 at 2 points p and q.the slope of l is 3/4.if l passes through3,7,find the coordinates of p and q and the equation of the diameter which is perpendicular to l.do with full calculations
Solution
First, let's simplify the equation of the circle by dividing it by 4:
x^2 + y^2 + 4.5x - 3y - 0.5 = 0
This can be rewritten in the standard form of a circle equation (x-h)^2 + (y-k)^2 = r^2, where (h,k) is the center of the circle and r is the radius. Completing the square for x and y terms:
(x^2 + 4.5x + (4.5/2)^2) + (y^2 - 3y + (3/2)^2) = 0.5 + (4.5/2)^2 + (3/2)^2
(x + 2.25)^2 + (y - 1.5)^2 = 6.25
So, the center of the circle is at (-2.25, 1.5) and the radius is √6.25 = 2.5.
The equation of the line l with slope 3/4 passing through (3,7) is:
y - 7 = 3/4 * (x - 3)
Solving for y gives:
y = 3/4x + 5.25
Substitute y from the line equation into the circle equation:
(x + 2.25)^2 + ((3/4x + 5.25) - 1.5)^2 = 6.25
Solving this quadratic equation will give the x-coordinates of points P and Q. Substitute these x-coordinates into the line equation to get the corresponding y-coordinates.
The diameter of the circle perpendicular to line l will have a slope of -4/3 (negative reciprocal of 3/4). The midpoint of a diameter of a circle is the center of the circle, so the equation of the diameter is:
y - 1.5 = -4/3 * (x + 2.25)
Solving for y gives the equation of the diameter:
y = -4/3x - 1.
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