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Rewrite sin(x+pi)+sin(x-pi) as a product.

This is for my trig class. Thanks for the help!

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Steve S. | Tutoring in Precalculus, Trig, and Differential CalculusTutoring in Precalculus, Trig, and Diffe...
5.0 5.0 (3 lesson ratings) (3)
1
Method 3.
 
Use Sum-To-Product Identity:
 
sin(u) + sin(v) = 2 sin((u+v)/2) cos((u-v)/2)
 
sin(x+pi) + sin(x-pi) = 2 sin(x) cos(pi) = -2 sin(x)
Robert J. | Certified High School AP Calculus and Physics TeacherCertified High School AP Calculus and Ph...
4.6 4.6 (13 lesson ratings) (13)
0
Method 1.
sin(x+pi)+sin(x-pi)
= 2sin x cos pi, after expanding and collecting like terms
= -2sin x
 
Method 2.
sin(x+pi)+sin(x-pi)
= -sin x - sin x, using reference angle
= -2sin x