maths

posted by Anonymous

1) Circle centre (7,-2) passes through (-2,10). Calculate radius and find equation of circle.

2) AB is diameter of circle A(9,5) B(-1,-7). Find equation of circle mid point.
I know i have to use the eqn (x1+x2)/2 and (y1+y2)/2

3) Find the equation of circle with centre (-8,5). Which has y axis as tangent. Find equation of circle.
?? (x+8)²+(y-5)²=r² ??

1. Damon

1)
The radius is the distance from the center , (7,-2), to the point (-2,10)
I bet you know the distance formula:
r^2 = (X2 - X1)^2 + (Y2 - Y1)^2
Then
(x-7)^2 +(y+2)^2 = r^2

2)
Yes, the center is at the average of those two points on opposite sides of the circle.
I think it is also asking for the equation of the circle.
Once you have found the center, you can find the equation the same way you found it in #1 but for r^2 use the distance^2 from center to one of those given points.

3)
The y coordinate of the center is 5.
Therefore the tangent to the y axis will be 8 units to the right of the center and at y = 5. (Draw a sketch) In other words at (0,5)
The radius is therefore 8 and r^2 = 64

Similar Questions

1. Geometry

Within an orthonormal system consider points A(1,4) B(5,1) C(4,8) (a)Calculate the angle ABC (b)Show that 3x+4y-19=0 is an equation for line L which passes through A and B (c)Find a vector equation for line L (d)(i)give an equation …
2. Maths

In an orthonormal system, you're given the following: Point P(1,2) Lina a=cartesian eqn:4x-3y+6=0 Line b=parametric eqns:x=-5+3& y=-& (real n°) Circle z=cartesian eqn:x²+y²-2x-3=0 (a)Calculate the angle between lines a an b (b)Calculate …
3. steev

can u help this the qustion is : A circle passes through the points (1,4)&(5,0) and its centre lies on the line x+y-3=0.Find (i) the equation of the circle and it parametric equations . (ii) the centre,diameter and area of the circle …
4. math

can u help this the qustion is : A circle passes through the points (1,4)&(5,0) and its centre lies on the line x+y-3=0.Find (i) the equation of the circle and it parametric equations . (ii) the centre,diameter and area of the circle …
5. mathematics

The circle x2-2x+y2-4y-4=0 lies on the cartesian plane,question 2.1.1 equation of new circle which is the rotation of original circle through 180 degree around the origin...2.1.2 find equation of another circle which is the translation …
6. mathematics

The circle x2-2x+y2-4y-4=0 lies on the cartesian plane,question 2.1.1 equation of new circle which is the rotation of original circle through 180 degree around the origin...2.1.2 find equation of another circle which is the translation …
7. mathematics

The circle x2-2x+y2-4y-4=0 lies on the cartesian plane,question 2.1.1 equation of new circle which is the rotation of original circle through 180 degree around the origin...2.1.2 find equation of another circle which is the translation …
8. mathematics

The circle x2-2x+y2-4y-4=0 lies on the cartesian plane,question 2.1.1 equation of new circle which is the rotation of original circle through 180 degree around the origin...2.1.2 find equation of another circle which is the translation …
9. maths

the centre of a circle is (2x-1,3x+1). find the x if the circle is passes thuthe centre of a circle is (2x-1,3x+1). find the x if the circle is passes through (-3, -1) and the length of its diameter is 20 units.gh (ro-3, -1) and the …
10. Math

The equation 2x^2+2y^2+x+4y+2c=0 represents a circle.(let's name it S1) 1)Find the values of a,b and and show that c<(17/16) 2)For positive integers of c,if the above circle is divided into two by, (x+p)^2=p^2 circle,find the value …

More Similar Questions