Answer:
Center is (3,4)
Radius is √55 which is approximately 7.42
Step-by-step explanation:
First, recall the equation for a circle. The equation for a circle is given by:
[tex](x-h)^2+(y-k)^2=r^2[/tex]
Where (h,k) is the center and r is the radius.
We have the equation:
[tex]x^2+y^2-6x-8y-30=0[/tex]
Thus, we want to turn this into the circle equation.
To do so, we need to complete the square.
First, put all the x-terms together and all the y-terms together. Also, add 30 to both sides:
[tex](x^2-6x)+(y^2-8y)-30=0\\(x^2-6x)+(y^2-8y)=30[/tex]
Now, complete the square for both of the variables. Recall how to complete the square. If we have:
[tex]x^2+bx[/tex]
We divide b by 2 and then square it. Then we will have a perfect square trinomial. To keep things balanced, we must also subtract what we added.
Thus, for the first term:
[tex](x^2-6x)\\=(x^2-6x+9)-9\\(x-3)^2-9[/tex]
And for the second term:
[tex](y^2-8y)\\=(y^2-8y+16)-16\\=(y-4)^2-16[/tex]
Replace the two terms:
[tex]((x-3)^2-9)+((y-4)^2-16)=30[/tex]
Simplify. Add -9 and -16:
[tex](x-3)^2+(y-4)^2-25=30[/tex]
Add 25 to both sides:
[tex](x-3)^2+(y-4)^2=55[/tex]
This is now in the form of the circle equation.
Thus, the center is (3,4).
And the radius is √55 which is approximately 7.42
