How to Calculate the Geometric Mean in Triangles

Step-by-step Guide: Geometric Mean in Triangles

1. Definition of Geometric Mean:
The geometric mean between two numbers, \(a\) and \(b\), is the square root of their product, represented as \(\sqrt{a \times b}\).

2. Geometric Mean in Right Triangles:

Altitude to the Hypotenuse: When an altitude is drawn to the hypotenuse of a right triangle, it creates two smaller triangles that are similar to the original triangle. The altitude serves as the geometric mean between the two segments it divides the hypotenuse into.

If the hypotenuse is divided into segments \(x\) and \(y\), and \(h\) is the length of the altitude, then:
\( h^2 = x \times y \)
\( h = \sqrt{x \times y} \)

Legs as Geometric Mean: In the same scenario, each leg of the right triangle is the geometric mean between the hypotenuse and the segment of the hypotenuse adjacent to the leg.

Examples

Example 1:
In a right triangle, if an altitude drawn to the hypotenuse divides it into segments of \(3 \text{ cm}\) and \(12 \text{ cm}\), find the length of the altitude.

Solution:
Using the property of geometric mean:
\( h = \sqrt{3 \times 12} \)
\( h = \sqrt{36} \)
\( h = 6 \text{ cm} \)

Example 2:
Given a right triangle with a hypotenuse of \(10 \text{ cm}\) and one segment of the hypotenuse being \(4 \text{ cm}\) (after drawing an altitude), determine the length of the leg adjacent to the \(4 \text{ cm}\) segment.

Solution:
Using the geometric mean property for legs:
\( \text{leg} = \sqrt{\text{hypotenuse} \times \text{adjacent segment}} \)
\( \text{leg} = \sqrt{10 \times 4} = \sqrt{40} \approx 6.32 \text{ cm} \)

Practice Questions:

1. If an altitude to the hypotenuse of a right triangle divides the hypotenuse into segments of \(5 \text{ cm}\) and \(20 \text{ cm}\), what is the length of the altitude?
2. In a right triangle with a hypotenuse of \(13 \text{ cm}\) and one segment of \(5 \text{ cm}\), find the length of the leg adjacent to the \(5 \text{ cm}\) segment.

Answers:

1. \( h = \sqrt{5 \times 20} = \sqrt{100} = 10 \text{ cm}\).
2. Leg length \(= \sqrt{13 \times 5} \approx 8.06 \text{ cm}\).