Cosine And Sine Rule

Normally the triangles in harder problems are not right angle triangles. When this occures we can use the sine and cosine rules.

**The Cosine Rule**

*a2=b2+c2- 2bccosA*

This rule allows us to find out any angle and length that is unknown as long as some of the lengths and angles are known in the triangle.

The cosine is used when we know the adjacent angle or side and the hypotenuse in the triangle.

**The Sine Rule**

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