The point (-2, -1) lies on a circle. What is the length of the radius of this circle if the center is located at (0, 4)?

Respuesta :

Answer:

The answer is 5 cm.

Step-by-step explanation:

Since the center is (0,4) and one of the point lies on (-2,-1),

4 - (-1) = 5 cm

The radius of a circle with center at  [tex]C (0, 4)[/tex] and point [tex]P(-2, -1)[/tex] will be [tex]\sqrt{29}[/tex].  

What is equation of a circle ?

Equation of a circle is written in the form of [tex](x-h)^2+(y-k)^2=r^2[/tex]  where [tex](h,k)[/tex]  represents the center and  [tex]r[/tex]  is the radius.

We have,

Center at  [tex]C (0, 4)[/tex]

i.e. [tex]h=0,\ k=4[/tex]

And,

Point  [tex]P(-2, -1)[/tex]

i.e. [tex]x=-2,\ y=-1[/tex]

Now,

To determine Radius of the circle;

[tex]r^2=(x-h)^2+(y-k)^2[/tex]

[tex]r^2=(-2-0)^2+(-1-4)^2[/tex]

[tex]r^2=(-2)^2+(-5)^2[/tex]

[tex]r=\sqrt{4+25}[/tex]

[tex]r=\sqrt{29}[/tex]

So, radius of the circle is [tex]\sqrt{29}[/tex] , which is find out using equation of a circle.

Hence, we can say that the radius of a circle with center at  [tex]C (0, 4)[/tex] and point [tex]P(-2, -1)[/tex] will be [tex]\sqrt{29}[/tex].

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