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Oblique Triangles: Law of Cosines
Introduction to Trig Functions
Domain, Range, and Period of Trig Functions
Graphs of Trigonometric Functions
Radians & Degrees
Trig Even-Odd Identities
Trig Reciprocal Identities
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Trig Product to Sum Identities
Trig Sum & Difference Identities
Oblique Triangles: Law of Cosines
Oblique Triangles: Law of Sines
Polar Coordinate System
Polar Equations & Graphs
De Moivre's Theorem
Oblique Triangles: Law of Cosines
The
law of cosines
relates the lengths of its sides to the cosine of one of its angles.
Referencing the above figure, the law of cosines may be written as:
The law of cosines should be used when:
Seeking length of third side upon knolwedge of two remaining sides and included angle
Seeking any angle upon knolwedge of all three sides
Example
:
For
a
= 5,
b
= 6, and γ = 30
^{o}
in figure below, determine remaining side
c
.
Solution
:
Related Topic
:
Law of Sines