Diameter of a circle joins...?

Question

The diameter of a circle joins the points (-1, -6) and (3, -9). Where is the centre of the circle located and what is the radius?

Answer 1

What is the length of the diameter? That way, you can find the radius (1/2 the diameter) and the center (midpoint of the diameter).

The diameter is five units long. How do we know? (-1) and (3) are separated by four units, and (-6) and (-9) are separated by three units. This forms a 3-4-5 right triangle, with the diameter being five units long.

The midpoint of this line segment is halfway between (-1) and (3), which is (1), and halfway between (-6) and (-9), which is (-7.5).

The radius = 2.5 units
Center = (1, -7.5)

Answer 2

Diameter is a line joining the 2 points of a circle through the centre of the circle.

The center divides the diameter in to 2 halves. So for finding the center It is enough to find the mid-point of the given 2 points.

the x-coordinate is 3-1/2 = 1
the y-coordinate is -6-9/2 = -15/2

Therefore the centre is (1,-15/2) or just (1,-7.5)

Just find the distance between the centre and any of the given 2 points to get the radius.

So the Radius works out to be 5 units.

Hope you can understand this.

Answer 3

midpoint of a section is found by: adding x's and dividing by 2 for x coordinate, add y's and divide by 2 for y coordinate...
-1+3= 2 /2 = 1
-6 + -9 = -15 /2 = -7.5

midpoint (1, -7.5)

length of line segment
is found using a^2 + b^2 = c^2
first, subtract first x from second, (3- -1 = 4) this is a (4).
then, subtract first y from second, (-9 - -6 = -3) this is b (-3).
then plug into formula. this will give you length of dianter. split in half for radius.

good luck.

Answer 4

Center: (1, -7.5)
Radius: 5