SOLUTION: Find the radius of a circle with center at (4,1) if a chord of length 4√2 is bisected at (7,4)

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Question 1202298: Find the radius of a circle with center at (4,1) if a chord of length 4√2 is bisected at (7,4)
Found 2 solutions by ikleyn, Edwin McCravy:
Answer by ikleyn(52776) About Me  (Show Source):
You can put this solution on YOUR website!
.
Find the radius of a circle with center at (4,1)
if a chord of length 4√2 is bisected at (7,4)
~~~~~~~~~~~~~~~~~~~~

Make a sketch.
In your sketch, find a right-angled triangle, which has the vertices OXY, where
O  is the center of the circle;  X  is the midpoint of the chord and 
Y  is  one of the two intersection points of the chord and the circle.


The leg XY of this triangle has the length 2%2Asqrt%282%29, half of the leg
of the chord; the leg OX is the vector with coordinates (3,3) = (7-4,4-1).
The length of this leg OX is  3%2Asqrt%282%29.


The radius "r" of the circle is the hypotenuse of this triangle

    r%5E2 = %282%2Asqrt%282%29%29%5E2 + %283%2Asqrt%282%29%29%5E2 = 4*2 + 9*2 = 8 + 18 = 26.


ANSWER.  The radius of the circle is  r = sqrt%2826%29 units.

Solved.



Answer by Edwin McCravy(20054) About Me  (Show Source):