SOLUTION: A chord 6 cm long is 2 cm from the center of a circle. How long is a chord that is 1 cm from the center of the same circle?

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Question 1156833: A chord 6 cm long is 2 cm from the center of a circle. How long is a chord that is 1 cm
from the center of the same circle?

Found 2 solutions by Boreal, ikleyn:
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
Draw this.
The triangle formed by the line from the center to the chord. (perpendicular bisector) is 2 and the other leg (half the chord's length) is 3. The radius is the hypotenuse and is sqrt(13) cm.
The other chord has leg 1 and hypotenuse sqrt(13)
so the other leg , half the chord, is sqrt (12) or 2 sqrt(3)
Length of the chord is 4 sqrt(3) cm.

Answer by ikleyn(52778) About Me  (Show Source):
You can put this solution on YOUR website!
.

Make a sketch.


Draw the perpendicular radius to the first chord.


Find right angled triangle in the sketch.


For this right angled triangle, write the Pythagorean formula


    r^2 = d^2 + L^2,    (1)


where r is the radius of the circle, d is the distance of the chord from the center of the circle 
and L is half the chord's length.


Then from (1) you get

    r^2 = 2^2 + (6/2)^2 = 4 + 3^2 = 4 + 9 = 13.


Thus the radius of the circle is  sqrt%2813%29.


Now write equation (1) for the chord, which is 1 cm from the center of the same circle

    13 = 1^2 + (x/2)^2 

where x the length of this chord.


You then get

    (x/2)^2 = 13 - 1 = 12;

    x/2 = sqrt%2812%29 = 2%2Asqrt%283%29


ANSWER.  The length of the cord is  4%2Asqrt%283%29 = 6.928 centimetres.