# Write the standard equation of the circle with center (-4, 3) and a radius of 5.?

Write the standard equation of the circle with center (-4, 3) and a radius of 5.

(x + 4)^2 + (y - 3)^2 = 5

(x - 4)^2 + (y + 3)^2 = 5

(x + 4)^2 + (y - 3)^2 = 25

(x + 3)^2 + (y - 4)^2 = 25

Earthquakes release seismic waves that occur in concentric circles from the epicenter of the earthquake. Suppose a seismograph station determines the epicenter of an earthquake is located 9 kilometers from the station. If the epicenter is located at the origin, write the equation for the circular wave that passes through the station.

x^2 + y^2 = 81

x^2 + y^2 = 9

(x - 9)^2 + (y - 9)^2 = 0

(x + 9)^2 + (y + 9)^2 = 0

### 2 Answers

- MichaelLv 71 month agoFavorite Answer
The standard equation for a circle is

(x - h)² + (y - k)² = r²

Where (h, k) is the center of the circle and r is the radius

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circle with center (-4, 3) and a radius of 5

( x - -4)² + (y - 3)² = 5²

(x + 4)² + (y - 3)² = 25 <––––––

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• the epicenter of an earthquake is located 9 kilometers from the station

r = 9

• epicenter is located at the origin

(h, k) = 0

(x - 0)² + (y - 0)² = 9²

x² + y² = 81 <––––––

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