CPM Homework Help : INT3 Problem 3-18

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Home > INT3 > Chapter Ch3 > Lesson 3.1.1 > Problem 3-18

3-18.

What are the center and radius of each circle? Rewrite the equations if necessary.

Hint:

Rewrite each equation in graphing form.

Help:

$(x-h)^{2}+(y-k)^{2}= \ r^{2}$

$(y-7)^2=25-(x-3)^2$
Answer (a):
center: $(3,7)$
radius: $5$

$x^2+y^2+10y=-9$
Hint (b):
Completing the square for $y$ is necessary.
Answer (b):
center: $(0,−5)$
radius: $4$

$x^2+y^2+18x-8y+47=0$
Hint (c):
Complete the square for both $x$ and $y$ .
Answer (c):
center: $(−9,4)$
radius: $\sqrt{50}$

$y^2+(x-3)^2=1$
Hint (d):
$(x−3)^2+(y−0)^2=1$

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