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A circle is centered at the point (-7, -1) and passes through the point (8, 7).

The radius of the circle is units. The point (-15, ) lies on this circle.

User Seifolahi
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2 Answers

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Radius is the distance from the centre to any point in the circumference. i.e. radius =
\sqrt{ (-7-8)^(2) + (-1-7)^(2) } = \sqrt{ (-15)^(2) + (-8)^(2) } \\ = √(225+64) = √(289) =17
radius = 17 units
User Brett Zamir
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Answer:

The radius of the circle is 17 units. The point (-15,-16) or (-15,14) lies on this circle.

Explanation:

It is given that the circle is centered at the point (-7, -1) and passes through the point (8, 7).

Distance formula:


D=√((x_2-x_1)^2+(y_2-y_1)^2)

Using distance formula we get,


r=√((8-(-7))^2+(7-(-1))^2)


r=√((15)^2+(8)^2)


r=17

The radius of the circle is 17 units.

Let the circle passing through the point (-15,y).


r=√((-15-(-7))^2+(y-(-1))^2)


17=√(64+(y+1)^2)

Taking square root both the sides.


289=64+(y+1)^2


289-64=(y+1)^2


225=(y+1)^2

Taking square root both the sides.


\pm √(225)=(y+1)


\pm 15-1=y


-16,14=y

The value of y is either -16 or 14.

Therefore the radius of the circle is 17 units. The point (-15,-16) or (-15,14) lies on this circle.

User Effreety
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