Question 16471
Use similar triangles to solve this problem.

The yard stick (1 yd = 3 ft.) is the vertical leg of one right triangle and its shadow (2 ft) is the base.
The tree (h ft.) is the vertical leg of the second right triangle  and its shadow (30 ft) is the base.

Recalling that "corresponding sides of similar triangles are proportional", you can form a proportion to find h, the height of the tree.

{{{3/2 = h/30}}} Multiply both sides by 30.
{{{h = 90/2}}} = 45 feet.