1. **State the problem:** A bird is 12 feet from the base of a tree and flies 20 feet to the top of the tree. We need to find the height of the tree. 2. **Identify the right triangle:** The bird's horizontal distance from the tree is one leg ($12$ feet), the height of the tree is the other leg (unknown, call it $h$), and the bird's flying distance is the hypotenuse ($20$ feet). 3. **Recall the Pythagorean theorem:** For a right triangle with legs $a$ and $b$, and hypotenuse $c$, the formula is: $$a^2 + b^2 = c^2$$ 4. **Apply the formula:** Let $a = 12$, $b = h$, and $c = 20$. $$12^2 + h^2 = 20^2$$ 5. **Calculate squares:** $$144 + h^2 = 400$$ 6. **Isolate $h^2$:** $$h^2 = 400 - 144$$ $$h^2 = 256$$ 7. **Find $h$ by taking the square root:** $$h = \sqrt{256}$$ $$h = 16$$ 8. **Answer:** The height of the tree is **16 feet**.