a flag 10 m long subtends a right angle on a pole 20 m away . find hieght of pole.
 
|
|90'
|---------------|
|                   |
|                   |
|                   |10m
|                   |
|                   |
|                   | 
|---------------|
        20m 
 

Asked by arunyadav6 | 2nd Aug, 2015, 12:52: PM

Expert Answer:

Q u e s t i o n space s h o u l d space b e colon A space p o l e space s u b t e n d s space a space r i g h t space a n g l e space o n space t h e space t o p space o f space a space f l a g space 10 space m space l o n g comma space w h i c h space i s space 20 m e t r e s space a w a y space f r o m space t h e space p o l e. F i n d space t h e space h e i g h t space o f space t h e space p o l e.  S o l u t i o n colon
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 C E D C D squared equals 20 squared plus 10 squared rightwards double arrow C D squared equals 500 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 A C D comma A C squared equals A D squared minus C D squared equals open parentheses 10 plus x close parentheses squared minus 500... left parenthesis 1 right parenthesis 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 A B C comma A C squared equals A B squared plus B C squared equals x squared plus 20 squared... left parenthesis 2 right parenthesis F r o m space e q u a t i o n s space left parenthesis 1 right parenthesis space a n d space left parenthesis 2 right parenthesis comma space w e space h a v e comma open parentheses 10 plus x close parentheses squared minus 500 equals x squared plus 20 squared rightwards double arrow 100 plus x squared plus 20 x minus 500 equals x squared plus 400 rightwards double arrow 20 x equals 800 rightwards double arrow x equals 800 over 20 rightwards double arrow x equals 40 space m T h u s comma space t h e space h e i g h t space o f space t h e space p o l e space i s space 10 plus x equals 10 plus 40 equals 50 space m

Answered by Vimala Ramamurthy | 3rd Aug, 2015, 10:29: AM