4.6. Law of Sines http://www.ck12.org
4.6 Law of Sines
Here you will further explore solving non-right triangles in cases where a corresponding side and angle are given
using the Law of Sines.
When given a right triangle, you can use basic trigonometry to solve for missing information. When given SSS or
SAS, you can use the Law of Cosines to solve for the missing information. But what happens when you are given
two sides of a triangle and an angle that is not included? There are many ways to show two triangles are congruent,
but SSA is not one of them. Why not?
Watch This
http://www.youtube.com/watch?v=APNkWrD-U1k Khan Academy: Proof: Law of Sines
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/58144http://www.youtube.com/watch?v=dxYVBbSXYkA James Sousa: The Law of Sines: The Basics
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/58146Guidance
When given two sides and an angle that is not included between the two sides, you can use the Law of Sines. The
Law of Sines states that in every triangle the ratio of each side to the sine of its corresponding angle is always the
same. Essentially, it clarifies the general concept that opposite the largest angle is always the longest side.
sinaA=sinbB=sincC
Here is a proof of the Law of Sines: