Law of Sines & Cosines

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Law of Sines & Cosines

Post Number: #1 by Jessica » March 21st, 2011, 4:19 pm

Law of Sines

If ABC is a triangle with sides a, b, and c, then
$\frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C}$

used for SSA, ASA, AAS

Area = $\frac{1}{2}bc\sin A = \frac{1}{2}ab\sin B = \frac{1}{2}ac\sin C$

Law of Cosines

used for SSS, SAS

a² = b² + c² − 2bccosA
b² = a² + c² − 2accosB
c² = a² + b² − 2abcosC

HERON'S AREA
$\sqrt{s(s-a)(s-b)(s-c)}$

where $s = (a + b + c)/2$