If you draw out the diagram, then you'll find that a 45-45-90 triangle forms. The nice thing about this type of triangle is that the two legs are always the same length. The horizontal leg is 100 meters, so the vertical leg must also be 100 meters.
Side note: this type of triangle is an isosceles right triangle.
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You could use the tangent rule to get the same thing
tan(angle) = opposite/adjacent
tan(45) = 100/x
1 = 100/x
1*x = 100
x = 100
In this case, the opposite leg is the vertical leg since it is furthest from the angle of elevation.
Both have 4 right angles. Both have 2 sets of parallel lines. Both have 4 equal sides.
But I think you are supposed to answer if figure 1 is similar to figure 2 and figure two is similar to figure 3 then by the transitive property, figure 1 is similar to figure 3.
