Trigonometric Ratios
Welcome to the Trigonometric Ratios chapter. Here we explore the fundamental relationships between the angles and side lengths of right-angled triangles.
Topics
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Introduction & Right Triangle Geometry
Learn what trigonometry means and how to identify the Hypotenuse, Opposite, and Adjacent sides of a right triangle.
Introduction & Right Triangle Geometry
Origin of the Name
The word Trigonometry comes from three simple Greek words:
- tri — meaning three
- gon — meaning sides
- metron — meaning measure
Together, trigonometry means measuring the three sides and angles of a triangle.
Parts of a Right-Angled Triangle
In a right-angled triangle, one angle measures exactly \(90^\circ\). We classify the three sides based on a chosen reference angle:
- Hypotenuse: The longest side of the triangle, located directly opposite the \(90^\circ\) right angle. It stays in the same position regardless of which acute angle you pick.
- Opposite Side: The side directly across from your chosen reference angle.
- Adjacent Side: The side next to your chosen reference angle (the side that forms the angle along with the hypotenuse).