The Law of Sines and the Law of
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The Law of Sines and the Law of Cosines Honors Advanced Algebra II with Trigonometry Mrs. Stacey
Essential Question • How do you solve triangles? Essential Vocabulary • Law of Sines • Law of Cosines • Solve a Triangle Free powerpoint template: www. brainybetty. com 2
Law of Sines • Gives a ratio that relates lengths of sides and measures of angles of triangles. Free powerpoint template: www. brainybetty. com 3
The Law of Sines • The Law of Sines is useful for finding the missing measures of the sides and angles of any triangle (right Δ or not). • Use when given (1) Two angles and any side or (2) Two sides and the angle opposite one of those sides Examples… Free powerpoint template: www. brainybetty. com 4
Why Law of Cosines? • Recall that the Law of Sines can only be used under two conditions… • However, for the triangle at right we cannot use the Law of Sines. 86 29° 72 Free powerpoint template: www. brainybetty. com 5
The Law of Cosines Free powerpoint template: www. brainybetty. com 6
Law of Sines & Cosines • Use the Law of Cosines when given… – Two sides and the angle between them – All three sides • Use the Law of Sines when given… – Two angles and any side – Two sides & the angle opposite one of those sides Examples… Free powerpoint template: www. brainybetty. com 7
Homework: Law of Sines and Law of Cosines Free powerpoint template: www. brainybetty. com 8
