Question 536279
{{{drawing( 200, 400, -30, 20, -35, 65,
  locate( 0, 0, Jon ),
  locate( -20, 0, X ), locate( -18, 60, rock ),

  triangle( 0, 0, 10, 0, 10, -30 ),
  triangle( -20, 0, 0, 0, -20, 60 ), 
  locate( 10, 0, turn ), locate( 10, -30, Sally )
  )}}}There are two similar triangles (two right angles,two angles congruent because they're vertical angles.
The larger triangles sides are twice the smaller's in length.