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WHEN A PLANE MIRRORIS PLACED HORIZONTALLY ON LEVEL GROUND AT A DISTANCE OF 60M FROM FOOT OF TOWER THE TOP OF THE TOWER AND ITS IMAGE IN MIRROR SUBSTENDS AN ANGLE OF 90 DEGREES .Find height of tower 30m 60m 90m 120m

WHEN A PLANE MIRRORIS PLACED HORIZONTALLY ON LEVEL GROUND AT A DISTANCE OF 60M FROM FOOT OF TOWER THE TOP OF THE TOWER AND ITS IMAGE IN MIRROR SUBSTENDS AN ANGLE OF 90 DEGREES .Find height of tower


30m


60m


90m


120m

Grade:9

1 Answers

vikas askiitian expert
509 Points
13 years ago

mirror is placed on horizontal ground ....

incidend ray & refracted ray are at 90o ...

angle substended by both rays with normal(verticle axis) of plane is same , so let this

angle be @ then

@ + @ = 90

@ = 45o

now using tan@ = h/d

tan45 = h/d

h = d

height of tower is same 60m......

option b is correct

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