Question: A bird was sitting 4 meters from the base of an oak tree and flew 5 meters to reach the top of the tree. How tall is the tree?
1. **State the problem:**
A bird is initially 4 meters from the base of an oak tree and flies 5 meters to reach the top of the tree. We need to find the height of the tree.
2. **Identify the formula and concept:**
This is a right triangle problem where the bird's initial position, the height of the tree, and the distance the bird flew form a right triangle.
Using the Pythagorean theorem:
$$a^2 + b^2 = c^2$$
where:
- $a$ is the height of the tree (unknown),
- $b$ is the horizontal distance from the base (4 meters),
- $c$ is the hypotenuse, the distance the bird flew (5 meters).
3. **Set up the equation:**
$$a^2 + 4^2 = 5^2$$
4. **Calculate:**
$$a^2 + 16 = 25$$
5. **Isolate $a^2$:**
$$a^2 = 25 - 16$$
$$a^2 = 9$$
6. **Find $a$ by taking the square root:**
$$a = \sqrt{9}$$
$$a = 3$$
7. **Conclusion:**
The height of the tree is $3$ meters.