http://www.ck12.org Chapter 8. Right Triangle Trigonometry
Use the second equation to solve for^6 B.
b^2 = 262 + 182 − 2 ( 26 )( 18 )cos 26◦
b^2 = 1000 −936 cos 26◦
b^2 = 158. 7288
b≈ 12. 60To findm^6 Aorm^6 C, you can use either the Law of Sines or Law of Cosines. Let’s use the Law of Sines.
sin 26◦
12. 60=
sinA
18
12. 60 ·sinA= 18 ·sin 26◦sinA=18 ·sin 26◦
12. 60sin−^1
( 18 ·sin 26◦
12. 60)
≈ 38. 77 ◦To findm^6 C, use the Triangle Sum Theorem.26 ◦+ 38. 77 ◦+m^6 C= 180 ◦
m^6 C= 115. 23 ◦Watch this video for help with the Examples above.
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/52524CK-12 Foundation: Chapter8LawsofSinesandCosinesB
Vocabulary
TheLaw of SinessayssinaA=sinbB=sincCfor any triangle (including non-right triangles). TheLaw of Cosinessays
a^2 =b^2 +c^2 − 2 bccosAfor any triangle.
Guided Practice
Find the following angles in the triangle bloew. Round your answers to the nearest hundredth.