Two parallel chords of lengths 30 cm and 16 cm are drawn on the opposite sides of the centre of a circle of a radius 17 cm. The distance between the chords is
A
32cm
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
23cm
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
C
46cm
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
16cm
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution
The correct option is B 23cm Given−Oisthecentreofacircleofradius17cm.AB=16cm&CD=30cmareparallelchordswhoareatperpendiculardistanceofPQ.Tofindout−PQ=?Solution−WejoinOCanddropperpendicularsOM&ONfromOtoAB&CD.OM&ONmeetAB&CDatM&Nrespectively.∴M&NaremidpointsofAB&CDrespectivelysincetheperpendicular,droppedfromthecenterofacircletoanyofitschordbisectsthelatter.SoAM=12×AB=12×16cm=8cmandCN=12×CD=12×30cm=15cm.NowOM⊥AB&ON⊥CD.∴∠OMA=90o=∠ONC.i.eΔOMA&ΔONCarerighttriangleswithOA&OCashypotenusesrespectively.So,byPythagorastheorem,wehaveOM=√OA2−AM2=√172−82cm=15cmandON=√OC2−CN2=√172−152cm=8cm.∴MN=OM+ON=(15+8)cm=23cm.NowAB∥CDandPQistheperpendiculardistancebetweenthem.AlsoOM&ONareonthesamestraightlineasbothofthemareperpediculartoapairofstraightlinesAB&CDandtheypassthroughthesamepointO.SoMNistheperpendiculardistancebetweenAB&CD.∴PQ=MN=23cm.Ans−OptionB.