Question 1101008
Assuming a horizontal ground, each object's and the object's shadow
can be visualized as the legs of a right triangle.
The hypotenuse would be along the ray of sunlight that grazes the top of the object,
and both hypotenuses make the same angle with the ground.
Having one pair of congruent acute acute angles,
makes both right triangles similar,
so their ratio of vertical leg to horizontal leg must be the same.
for the tower,  {{{height/"7 m"=5m/"2 m"}}} .
{{{height=(7 m)(5m)/"2 m"}}} .
{{{height=highlight(17.5m)}}} .