Question

PLS PLS HELP WILL GIVE 50 POINTS TO BRAINLIEST How do you find the radius of a circle with the equation: 03.5 (x+2.2)^2 + 3.5 (y−11.1)^2 − 21 = 0

Answer 1

Answer: r=√6 or r≈2.45.

Step-by-step explanation:

To find the radius, you first need to know the equation of a circle.

Equation of a circle: $(x-h)^2+(y-k)^2=r^2$

Now that we know the equation of the circle, we can use it to find the radius of the given equation.

3.5(x+2.2)²+3.5(y-11.1)²-21=0

So far the equation looks pretty similar with the exception of the bolded areas. To get rid of them, we need to use our algebraic properties.

3.5(x+2.2)²+3.5(y-11.1)²-21=0                    [add both sides by 21]

3.5(x+2.2)²+3.5(y-11.1)²=21                       [factor out 3.5]

3.5((x+2.2)²+(y-11.1)²)=21                           [divide both sides by 3.5]

(x+2.2)²+(y-11.1)²=6

Now, our equation is the same as the one posted above. You may think that 6 is our radius, but if you look closely, the equation is equal to r². Therefore, 6 is actually r², not r.

r²=6                                                             [square root both sides]

r=√6

Finally, we have the final answer, r=√6 or r≈2.45.