Question 197782
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If you know the measure of the diameter, you simply divide by 2 to get the measure of the radius.  Knowing the endpoints of a segment allows you to find the measure of the segment by use of the distance formula:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ d = sqrt{(x_1 - x_2)^2 + (y_1 - y_2)^2}]


where *[tex \Large (x_1,y_1)] and *[tex \Large (x_2,y_2)] are the coordinates of the given points.  In this case, the endpoints of your diameter.  Just plug in the values and do the arithmetic.


The circumference of a circle is given by the formula:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ C = 2\pi r]


But you can solve this formula for *[tex \Large r] and then use it to find the radius when you know the circumference.  Just divide both sides by *[tex \Large 2\pi]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ r = \frac{C}{2\pi}]


Again, just plug in the numbers you know and do the arithmetic.



John
*[tex \LARGE e^{i\pi} + 1 = 0]
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