Question 773269

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Given a circle with radius 5cm and chord AB, measuring 6cm, find the perpendicular distance of "d" between AB and the center of the circle.

Ans:
Remember that: The perpendicular "d" from the center of the circle to the chord, bisects the chord.
Let the centre of the circle be O, and the point where d cuts AB be called C.
Now:
d, CB (half the chord) and OB (radius) form a right triangle with OB as the 
hypotenuse.
OB = 5
CB = half of AB = 3
Applying Pythagoras theorem
d^2 = OB^2 - CB^2 = 25 - 9 = 16
Therefore d = 4 cm.
Hope you got it :)
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