Archive
14th of September 2015
Mathematics
Q:

FIND THE AREA OF THE REGION BOUNDED BY TWO CONCENTRIC CIRCLES IF THE LENGTH OF THE CHORD OF THE OUTER CIRCLE ,TOUCHING THE INNER CIRCLE ,IS 28CM.

Sowparnika S - ICSE - Class X

Wednesday, September 09, 2015 at 20:35:PM

A:

C o n s i d e r space t h e space a b o v e space f i g u r e. T h e space c h o r d space A B space o f space t h e space b i g g e r space c i r c l e space i s space a space tan g e n t space t o space t h e space s m a l l e r space c i r c l e. L e t space apostrophe R apostrophe space b e space t h e space r a d i u s space o f space t h e space b i g g e r space c i r c l e. A n d space apostrophe r apostrophe space b e space t h e space r a d i u s space o f space t h e space s m a l l e r space c i r c l e. C o n s i d e r space t h e space r i g h t space t r i a n g l e space O B C. B y space a p p l y i n g space P y t h a g o r a s space T h e o r e m comma space w e space h a v e comma R squared equals r squared plus 14 squared rightwards double arrow R squared minus r squared equals 14 squared rightwards double arrow R squared minus r squared equals 196 A r e a space o f space t h e space r e g i o n space b o u n d e d space b y space t h e space c o n c e n t r i c space c i r c l e s equals straight pi open parentheses straight R squared minus straight r squared close parentheses equals 196 straight pi space sq. cm

Thursday, September 10, 2015 at 11:16:AM