Difference between revisions of "Trigonometry Functions"
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→Arccosine
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See above for method of obtaining arcsin. This may be useful when using the Law of Cosines to find the measure of an unknown angle, given three known sides. | See above for method of obtaining arcsin. This may be useful when using the Law of Cosines to find the measure of an unknown angle, given three known sides. | ||
<b><u>Law of Cosines</u></b> | |||
<i>a</i><sup>2</sup> = <i>b</i><sup>2</sup> + <i>c</i><sup>2</sup> - 2<i>bc</i> cos<i>A</i> | |||
<i>b</i><sup>2</sup> = <i>a</i><sup>2</sup> + <i>c</i><sup>2</sup> - 2<i>bc</i> cos<i>B</i> | |||
j<i>c</i><sup>2</sup> = <i>a</i><sup>2</sup> + <i>b</i><sup>2</sup> - 2<i>ab</i> cos<i>C</i> | |||
That is, the square of one side is equal to the sum of the other squares of the other two, minus twice the product of the other two sides with the cosine of the angle opposite that side. | |||
Simple algebra gives the following equations for any given angle in a triangle, if you know the lengths of all three sides. | |||
[[Image:LawOfCosinesForAngle.png]] | |||
= Arctangent = | = Arctangent = | ||