8. A circle with center (2,−5) is tangent to the x-axis.
a. What is the radius of the circle?
b. What is the equation of the circle?

Respuesta :

Answer:

r = 2

equation of the circle: [tex](x-2)^2+(y+5)^2=4[/tex]

Step-by-step explanation:

a) given the center of the circle as (2,-5).

we can say that

  • the centre is 2 units above the x-axis and
  • 5 units to the left of the y-axis

it is also given that the circle is tangent to the x-axis, this means that the circle touches the x-axis.

And we already know how far away the circle's center is from the x-axis, i.e. 2 units. Hence this is the radius.

r = 2.

b) Given the center of the circle we can its equation using the formula

[tex](x-a)^2+(y-b)^2=r^2[/tex]

where, (a,b) are the coordinates of the center of the circle. and r is the radius

hence (a,b) = (2,-5) and r = 2

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

[tex](x-2)^2+(y+5)^2=4[/tex]

this is the equation of the circle!