In a circle of diameter 20 cm, chords AB and CD are parellel to each other, BC is diametter . If AB is 6 cm from center of the circle what is the length ( in cm) of the chord CD ?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 16
AB and CD are parallel to each other and BC is diameter = 20 cm
∵ let O is the center and draw OP on AB which will make a right angle with chord AB and the same as draw OQ on CD which will make a right angle with chord CD.
radius r=OA = OC = 10 cm
OP= 6 cm
AP = AB/2
in triangle OAP , OA2 = OP2 + AP2
102= 62 + AP2
AP2 = 100-36 =64
AP = 8
AB = 8 * 2 = 16
∵ AB and CD are parallel so AB = CD = 16 cm.