Asked by -
Prove that:
2sinxsiny = cos(x-y) - cos(x+y)
2sinxsiny = cos(x-y) - cos(x+y)
Answers
Answered by
drwls
Rewrite the right side, using
cos (x + y) = cos x cos y - sin x sin y
cos (x - y) = cos x cos y + sin x sin y
You should be familiar with those two identities.
cos (x + y) = cos x cos y - sin x sin y
cos (x - y) = cos x cos y + sin x sin y
You should be familiar with those two identities.
Answered by
nando
kagr
Answered by
Simone
To price this equation first subtract cos(x-y) and cos(x+y)
=cosXcosY + sinXsinY
-(cosXcosY-sinXsinY)
= 2sinXsinY
Hence , proved!
=cosXcosY + sinXsinY
-(cosXcosY-sinXsinY)
= 2sinXsinY
Hence , proved!