Cosine Rule Lesson

Cosine Rule (or Law of Cosines)

Conventions

​The same convention for labels is followed

It is important to keep the conventional labelling process in mind when interpreting the formula and information provided in diagrams.

Angles and their opposite sides are paired as upper and lower case letters.

​Statement of the Cosine Rule

​The next three slides will take you to Khan Academy video example and a short quiz. Come back to the Quizizz tab when done.

Law of cosines: solving for a side | Trigonometry (video) | Khan Academy

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Law of cosines: solving for an angle | Trigonometry (video) | Khan Academy

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Solve triangles using the law of cosines (practice) | Khan Academy

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Multiple Choice

• 6.3

• 7.3

• 11.8

• 7.2

Multiple Choice

• 2.9

• 6.5

• 11.3

• 7.1

Multiple Choice

• 6.8

• 8.1

• 8.6

• 7.5

Multiple Choice

• 44.2

• 37.5

• 38.2

• 41.8

Multiple Choice

• 44.4

• 37.5

• 38.2

• 41.8

Multiple Choice

• 53.2

• 51.3

• 48.7

• 49.7