Suppose that the boom of a gun is recorded by three microphones: Let's call them A, B and C. Assume that the three microphones are spaced 386 meters (1,266 feet) apart. That is the distance sound travels through air in one second. The boom reaches microphone A first. One second later it reaches microphone B. One second after that it reaches C. Draw a circle with a radius equal to 386 meters centered on B and a circle with radius twice that distance centered on C. Now draw a circle that goes through the position of microphone A and that also touches the two other circles. The center of this circle is the position of the gun that fired.
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radius A straight line from the center to the circumference of a circle or sphere.
range The full extent or distribution of something. For instance, a plant or animal’s range is the area over which it naturally exists. (in math or for measurements) The extent to which variation in values is possible. Also, the distance within which something can be reached or perceived.
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