He points ​(-9​,-4​) and ​(3​,6​) are the endpoints of the diameter of a circle. Find the length of the radius of the circle.

Respuesta :

First end point of the diameter of a circle = ​(-9​,-4​).

Second end point of the diameter of a circle = ​(3​,6​).

Let us find length of the of the diameter of the circle by using distance formula.

We know distance formula,

[tex]d= \sqrt{(x_2 - x_1)^2+ (y_2 - y_1)^2}[/tex]

We have (x1, y1) =  ​(-9​,-4​) and (x2,y2) = ​(3​,6​).

Plugging values of x1,y1, x2 and y2 in above distance formula.

[tex]Distance = \sqrt{(3-(-9))^2+ (6 - (-4))^2}[/tex]

= [tex]\sqrt{(3+9)^2 +(6+4)^2} = \sqrt{(12)^2+(10)^2}[/tex]

[tex]=\sqrt{144+ 100}[/tex]

[tex]=\sqrt{244}[/tex]

Factoring out heighest perfect square from 244.

244= 4* 61.

[tex]\sqrt{244} = \sqrt{4 * 61}  = \sqrt{4} * \sqrt{61}[/tex]

Square root of 4 is 2.

[tex]\sqrt{4} * \sqrt{61} = 2 \sqrt{61}[/tex]

Therefore, diameter of the circle = [tex]2\sqrt{61}[/tex]

Radius is half of diameter.

So, dividing value of diameter by 2, we get

Radius =[tex]\frac{2\sqrt{61}}{2}=\sqrt{61}[/tex]