# Trigonometry

by
**quynguyen**

Last updated 6 years ago

** Discipline: **

Math ** Subject: **

Geometry
** Grade:**

7,8

Basic Trigonometry

Trigonometry from the greek word, trigōnon meaning triangle and measurement. It is a branch in mathematics that studies the relationship between triangles lengths and angles (Lial. M, 1977).

Refrences:Lial, M. (2008). Trigonometry: 9th Edition. America, USA: Pearson

The rules of Trigonometry:sinƟ= opposite/hypoteusecosƟ=adjacent/hypotenusetanƟ=oppositve/adjacent

A right angle triangle!

SOH=sine

CAH=cosine

TOA=tangent

Trigonometry can only work with right angle triangles. Meaning, SOH CAH TOA can only be used to solve out these triangles. This helps you work out unknown side lengths or unknown angles in a right-angled triangle.This video is a tutorial on how to apply this rule.

Example of a Cosine question:

As you can see, the question is asking us to find the angle ''C''.Therefore, we figure out which rule applies to the triangle and solve for C. Hence, the answer is the sinƟ rule. Opposite over hypotenuse (6/10).

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