Answer 5 :-
To find:-
- Distance of swimmer from lifeguard.
Answer:- 
We are here given that the line of sight is 8ft above the ground and the angle of depression is 18° . So ,

as these are alternate interior angles. 
Now in ∆ABC ,





Hence the horizontal distance of the swimmer from the lifeguard is 24.61 ft.
Also , there is a second distance of the swimmer from the lifeguard that is along AC , 




Hence the distance of the swimmer from the lifeguard along AC is 25.89ft .
 
 
Answer 6 :-
To find:-
- The altitude of the helicopter.
Answer :-
We are here given that the angle of depression is 73° . Therefore here ,

as they are alternate interior angles.
Now in ∆PQR , we have;





Hence the altitude of the helicopter is 3924 ft .
and we are done!