English

Show that the Points (5, 5), (6, 4), (−2, 4) and (7, 1) All Lie on a Circle, and Find Its Equation, Centre and Radius. - Mathematics

Advertisements
Advertisements

Question

Show that the points (5, 5), (6, 4), (−2, 4) and (7, 1) all lie on a circle, and find its equation, centre and radius.

Advertisements

Solution

Let the required equation of the circle be

\[x^2 + y^2 + 2gx + 2fy + c = 0\] ...(1)
It is given that the circle passes through (5, 5), (6, 4), (−2, 4).
∴ \[50 + 10g + 10f + c = 0\] ...(2)
\[52 + 12g + 8f + c = 0\] ...(3)
\[20 - 4g + 8f + c = 0\] ...(4)
Solving (2), (3) and (4):
\[g = - 2, f = - 1, c = 20\]
Thus, the equation of the circle is
\[x^2 + y^2 - 4x - 2y - 20 = 0\]  ...(5)
We see that the point (7, 1) satisfies equation (5).
Hence, the points (5, 5), (6, 4), (−2, 4) and (7, 1) lie on the circle.
Also, centre of the required circle = \[\left( 2, 1 \right)\]
Radius of the required circle = \[\sqrt{4 + 1 + 20} = 5\]
shaalaa.com
Advanced Concept of Circle - Standard Equation of a Circle
  Is there an error in this question or solution?
Chapter 24: The circle - Exercise 24.2 [Page 32]

APPEARS IN

RD Sharma Mathematics [English] Class 11
Chapter 24 The circle
Exercise 24.2 | Q 6 | Page 32

RELATED QUESTIONS

Find the equation of the circle with:

Centre (−2, 3) and radius 4.


Find the equation of the circle with:

Centre (0, −1) and radius 1.


Find the centre and radius of each of the following circles:

x2 + y2 − x + 2y − 3 = 0.


Find the equation of the circle passing through the point of intersection of the lines x + 3y = 0 and 2x − 7y = 0 and whose centre is the point of intersection of the lines x + y + 1 = 0 and x − 2y + 4 = 0.


Find the equation of a circle
which touches both the axes at a distance of 6 units from the origin.


Find the equation of a circle
which touches both the axes and passes through the point (2, 1).


Find the equation of a circle
passing through the origin, radius 17 and ordinate of the centre is −15.


Find the equation of the circle which has its centre at the point (3, 4) and touches the straight line 5x + 12y − 1 = 0.


Find the equation of the circle which touches the axes and whose centre lies on x − 2y = 3.


A circle of radius 4 units touches the coordinate axes in the first quadrant. Find the equations of its images with respect to the line mirrors x = 0 and y = 0.


Find the equations of the circles touching y-axis at (0, 3) and making an intercept of 8 units on the X-axis.


If the line y = \[\sqrt{3}\] x + k touches the circle x2 + y2 = 16, then find the value of k


Find the equation of the circle having (1, −2) as its centre and passing through the intersection of the lines 3x + y = 14 and 2+ 5y = 18.


The circle x2 + y2 − 2x − 2y + 1 = 0 is rolled along the positive direction of x-axis and makes one complete roll. Find its equation in new-position.


Find the equation of the circle passing through the points:

(5, 7), (8, 1) and (1, 3)


Find the equation of the circle passing through the points:

 (0, 0), (−2, 1) and (−3, 2)


Show that the points (3, −2), (1, 0), (−1, −2) and (1, −4) are concyclic.


Find the equation of the circle which passes through the origin and cuts off chords of lengths 4 and 6 on the positive side of the x-axis and y-axis respectively.


Find the equation to the circle which passes through the points (1, 1) (2, 2) and whose radius is 1. Show that there are two such circles.


If a circle passes through the point (0, 0),(a, 0),(0, b) then find the coordinates of its centre.


Find the equation of the circle, the end points of whose diameter are (2, −3) and (−2, 4). Find its centre and radius.


Find the equation of the circle circumscribing the rectangle whose sides are x − 3y = 4, 3x + y = 22, x − 3y = 14 and 3x + y = 62.


Find the equation of the circle whose diameter is the line segment joining (−4, 3) and (12, −1). Find also the intercept made by it on y-axis.


The abscissae of the two points A and B are the roots of the equation x2 + 2ax − b2 = 0 and their ordinates are the roots of the equation x2 + 2px − q2 = 0. Find the equation of the circle with AB as diameter. Also, find its radius.


Find the equations of the circles which pass through the origin and cut off equal chords of \[\sqrt{2}\] units from the lines y = x and y = − x.


Write the length of the intercept made by the circle x2 + y2 + 2x − 4y − 5 = 0 on y-axis.


Write the coordinates of the centre of the circle passing through (0, 0), (4, 0) and (0, −6).


The radius of the circle represented by the equation 3x2 + 3y2 + λxy + 9x + (λ − 6) y + 3 = 0 is


The number of integral values of λ for which the equation x2 + y2 + λx + (1 − λ) y + 5 = 0 is the equation of a circle whose radius cannot exceed 5, is


If the point (2, k) lies outside the circles x2 + y2 + x − 2y − 14 = 0 and x2 + y2 = 13 then k lies in the interval


The equation of the incircle formed by the coordinate axes and the line 4x + 3y = 6 is


If the circles x2 + y2 = 9 and x2 + y2 + 8y + c = 0 touch each other, then c is equal to


If the circle x2 + y2 + 2ax + 8y + 16 = 0 touches x-axis, then the value of a is


The circle x2 + y2 + 2gx + 2fy + c = 0 does not intersect x-axis, if


The equation of the circle which touches the axes of coordinates and the line \[\frac{x}{3} + \frac{y}{4} = 1\] and whose centres lie in the first quadrant is x2 + y2 − 2cx − 2cy + c2 = 0, where c is equal to


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×