Trigonometry+Content+in+the+Syllabus+for+Mathematics+D+for+Year+10+in+Brunei+Darussalam

Solving trigonometry can be divided into two - solving a right angle triangle or a non-right angle triangle.

First we need to identify the type of triangle we are dealing with.

A. If the triangle is a right angle triangle , to find the 1. **length**, given information is, only the length and no angle therefore we need to use Pythagoras Theorem, c2 = a2 +b 2.



2. **angle or length**, given that an angle and a length therefore we need to use S = O/H, C = A/H, T = O/A



3. **area**, use the formula, Area of Triangle = 1/2 x base x height

B. If the triangle is a non-right angle triangle , to find the 1. **angle or length**, we need to use either **SINE RULE** or **COSINE RULE**.


 * Cosine rule**: c2 = a2 + b2 - 2ab sin C


 * Sine rule**: Sin A/a = Sin B/b = Sin C/c

Capital letter represent the respective angle and small letter represent the length.

2. **area**, use the formula of, Area of a non-right angle triangle = 1/2 ab sin C