Question 216633: write the standard form of the equation of the circle that is tangent to the line x=3 and has center at (-2,-7)
a)(x-2)^2 + (y+7)^2 =25
b)(x-2)^2 + (y+7)^2 =5
c)(x-2)^2 + (y+7)^2 =16
d)(x+2)^2 + (y-7)^2 =25
Answer by RAY100(1637)   (Show Source):
You can put this solution on YOUR website! basic form of the circle eqn is, (x-h)^2 +(y-k)^2 = r^2,,,,with r =radius, (h,k) as center,,,,,note (plus and minus signs)
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Radius is found from horizontal distance from center to x=3 line
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radius is ( 3 - (-2) ) = 5
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(h,k) = (-2,-7),,,or h=(-2),,,and k=(-7)
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subst in basic form
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{x-(-2)}^2 + {y-(-7)}^2 =(5)^2
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{x+2)^2 + {y+7}^2 =25,,,,,which does not match any of the given answers
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pls check answer d for signs
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