CAT 2018 Question Paper | CAT Verbal Ability Slot 1
Question :

In a circle, two parallel chords on the same side of a diameter have lengths 4 cm and 6 cm. If the distance between these chords is 1 cm, then the radius of the circle, in cm, is

Started 3 months ago by Shashank in

Option A is the correct answer.

Explanatory Answer

 

Given that Chords lie on the same side of diameter with lengths 4 cms and 6 cms 
Draw a perpendicular from the origin to both the chords and mark the points of intersection as P
and Q respectively 
Consider radius of circle as ‘r’ and distance OP as ‘x’ 
Draw lines from origin to the end of the chord and mark the points as D and B respectively 
Thus, △OQB and △OPD form a right Triangle 
Applying Pythagoras Theorem on both triangles, 
(x+1) 2 +2 2 = r 2 ---(1) 
x 2 +3 2 = r 2 ---(2) 
We find that there is an increase and decrease by 1 in both equations 
So, x 2 = 2 2 , x=2 
r 2 = 2 2 +3 2 = 4+9 = 13 
r = √13 cms

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