# geometry

posted by .

hich is the equation of a circle with diameter AB with A(5,4) and B(-1,-4)?
(x-5)^2+(y-4)^2=10
(x+5)^2+(y+4)^2=100
(x-2)^2+y^2=25
(x+2)^2+y^2=5
Not sure

• geometry -

Standard equation of a circle with a radius of r and centre (x0,y0) is:
(x-x0)²+(y-y0)²=r²

Centre of circle:
((5-1)/2, (4+(-4))/2)=(2,0)
Out of the four choices, there is only one that has a centre positioned at (2,0).
(hint: refer to the standard equation of the circle)

Radius of circle = distance from centre to circumference
r = sqrt((5-2)^2+(4-0)^2)=5

This confirms the choice above.
(hint: refer to the standard equation of the circle)

• geometry -

This is what I have but not sure if right
(x-(-2)^2+(y-3)^2=5^2
(x+2)^2+(y-3)^2=25

• geometry -

I do not have the same answer as you.

If AB is the diameter, the centre is located at the mid-point between A and B.

The mid-point between A and B is
((Xa+Xb)/2, (Ya+Yb)/2)=(2,0)

I do not know how you got -2 and 3 for the centre of the circle. Can you explain?

• geometry -

I was looking at wrong problem for this one a I got (x+5)^2+(y+4)^2=100

• geometry -

Hint:
Centre of circle is at:
((5-1)/2, (4+(-4))/2)=(2,0)

• geometry -

(x+2)^2+y^2=5

• geometry -

1. Centre is at (2,0)
but
(x+2)^2+y^2=5
has a centre at (-2,0)

2. radius is 5, so the right hand side should be 5^2=25.

• geometry -

Now I'm definitely lost would you mind explaining the whole process so I might understand?

• geometry -

I guess you have not read this on Sunday:

Standard equation of a circle with a radius of r and centre (x0,y0) is:
(x-x0)²+(y-y0)²=r²

Centre of circle:
((5-1)/2, (4+(-4))/2)=(2,0)
Out of the four choices, there is only one that has a centre positioned at (2,0).
(hint: refer to the standard equation of the circle)

Radius of circle = distance from centre to circumference
r = sqrt((5-2)^2+(4-0)^2)=5

This confirms the choice above.
(hint: refer to the standard equation of the circle)

• geometry -

Okay, 9+16=25
so would my answer be (x-2)^2+(y^2)=25
I thiught you had to take the square rt of 25

• geometry -

Yep, you got it, congrats!
I hope you understand how it works.
If not, feel free to post.

• geometry -

The answer is (x-2)2+y2=25 i just took it on my quiz and all the other answers are wrong!!! so i got it wrong at first!! but this is the correct one!

## 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. ### Algebra II

In this set of eight problems, we have to match each equation with the correct description of its graph. However, these are test corrections I'm doing and I do not have the previous multiple choice answers so I can deduct from it, …
3. ### geometry

I need to find the area of the shaded portion of a circle with a square in the middle all corners touching the circle. My square has a line measurement of 10 cm. I know that the area of the square is 100 cm(10 x 10). But I am not sure …
4. ### Calculus

Points (–1, 6) and (–3, 2) are endpoints of the diameter of a circle. (a) What is the exact length of the diameter?
5. ### Geometry

Need help please: (3,0) (7,6) (x-7)2 + (y-6)2 = 7(2) (x-7)2 + (y-6)2 = 49 Having difficulty with this problem.Can someone help?
6. ### Geometry

Need help please: (3,0) (7,6) (x-7)2 + (y-6)2 = 7(2) (x-7)2 + (y-6)2 = 49 Having difficulty with this problem.Can someone help?
7. ### geometry

m<S=30, m(arc)RS=84,and RU is tangent to the circle at R find m<U. It's a circle with a triangle inscribed, only the s and r lie on the circle and u extends past circle. can someone help i do not know or understand these problems …
8. ### geometry

Name the diameter, radius, center, and the equation of the circle with a diameter that has endpoints at (-3, 4) and (5, -2).
9. ### geometry

2. For the circle with equation (x – 2)2 + (y + 3)2 = 9, answer each question: a) What are the coordinates of the center?
10. ### Geometry

Which is the equation of a 20 cm diameter circle with its center at (3, -6)?

More Similar Questions