MPM2D Cosine Law – 2016-01-19

Yup, today was Cosine Law. If you have a triangle ABC with opposite corresponding sides abc , you can find a missing side c using

c^2 = a^2 + b^2 - 2ab\cos(C)

You need to know the lengths of a and b and the angle C to do this.

You can also use the Cosine Law to find any missing angle if you know the lengths of all of the sides. In the above form, you can find angle C by substituting the side lengths and rearranging.

Your homework tonight is to complete Page 409 #2 and Page 418 #2.


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