Depth of the Lake a .
Let be , depth of the lake = x length of the reed = x + 100 length of the reed under water : x + 20 x 2 + 100 2 = ( x + 20 ) 2 x 2 + 10000 = x 2 + 40x + 400 10000 - 400 = 40x x = 9600 : 40 = 240cm
b .
Let be , depth of the lake = x length of the reed = x + a length of the reed under water : x + c x 2 + b 2 = ( x + c ) 2 x 2 + b 2 = x 2 + 2xc + c 2 b 2 - c 2 = 2xc x = ( b 2 - c 2 ) : 2c
Depth of the Lake a .
Let be , depth of the lake = x length of the reed = x + 100 length of the reed under water : x + 20 x 2 + 100 2 = ( x + 20 ) 2 x 2 + 10000 = x 2 + 40x + 400 10000 - 400 = 40x x = 9600 : 40 = 240cm
b .
Let be , depth of the lake = x length of the reed = x + a length of the reed under water : x + c x 2 + b 2 = ( x + c ) 2 x 2 + b 2 = x 2 + 2xc + c 2 b 2 - c 2 = 2xc x = ( b 2 - c 2 ) : 2c
Authors : Esma T . Bennu K .