Question

In the figure, find the value of CF.

Answer 1

LINE OF SIGHT: The line of sight is a line drawn from the eye of an observer to the point in the object viewed by the observer.

ANGLE OF ELEVATION: The angle of elevation of an object viewed is the angle formed by the line of sight with the horizontal , when it is above the horizontal level.

ANGLE OF DEPRESSION:The angle of depression of an object viewed is the angle formed by the line of sight with the horizontal , when it is below the horizontal level.

•Angle of elevation and depression are always acute angles.
•If the observer moves towards the perpendicular line(Tower/ building) then angle of elevation increases and if the observer move away from the perpendicular line(Tower/ building) angle of elevation decreases.

SOLUTION:
GIVEN:
AB = FD = 5 m (sides of a rectangle)
AF = BD= 20 m m (sides of a rectangle)
∠CBD = 45°

In ∆CBD ,
tan 45° = P/B = CD/ BD
1 = CD /20          [tan 45° = 1]
CD = 20 m
CF = CD + DF
CF = 20 + 5        [AB = FD = 5 m]
CF = 25 m

Hence, the value of C is 25 m.

HOPE THIS WILL HELP YOU...

Answer 2

25 m is the answer .
CF= CD + DF
BY
TAN 45° = CD/ BD [ tan45° = 1]
=> CD= 20m
=> CF= 20+5= 25m