Consider the two platforms are
and
.
The base is
.
Redraw the diagram :
\
Observe the figure :
\Two parallel lines are cut by a transversal, then consecutive angles are supplementary.
\Therefore, 
.
From the figure
.
The sum of the angles in any triangle is
.
The two angles are
and
.
The remaining angle
.

Therefore ,
and
and
.
Law of sines :
.


.
And
,
and 
Law of sines :
.



Therefore, the distance from the base to platform 2 is 
The distance from platform 1 to platform 2 is
.
The distance from the base to platform 2 is
.
The distance from platform 1 to platform 2 is
.