# Cosine Rule

 Cosine Rule find a Side Using the Cosine rule a2 = b2 + c2 - 2bcCos(A) to find an unknown side Khan Academy Videos: Pythagoras Iintroduction & Example and problems to practice MR notes, Blank notes p435 Ex 31.01 p436 Ex 31.02 Youtube proof of Cosine rule p139 Cosine rule to find a Side (java) 9 Cosine Rule find an Angle Using the Cosine rule to find an unknown angle in a non-right angle triangle MR notes, Blank notes p439 Ex 31.03 p439 Ex 31.04 Youtube proof of Cosine rule p140 Cosine rule to find an Angle (java) Cosine Rule Applications Using the Cosine rule to solve application problems involving finding sides or angles MR notes, Blank notes p442 Ex 31.05 p442 Ex 31.06 p141 & 142

## Overview

### The Cosine rule links THREE SIDES and ONE ANGLE in a triangle

 Rule Find Angles Find Sides Mouse over key words  ## Find a Side

### Cosine rule to find a Side (java)

 Rule Find Side Mouse over key words  ## Find an Angle

### Cosine rule to find an Angle (java)

 Rule Working Find Angle Mouse over key words  ## Solution

Mouse over key words  