cos(a-b) +cos(a+b)=2cosacosb
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Hello dear
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We know that
cos( a - b ) = cosacosb + sinasinb
cos( a + b ) = cosacosb - sinasinb
now
RHS
cos ( a - b ) + cos ( a + b )
cosacosb + sinasinb + cosacosb - sinasinb
= cosacosb + cosacosb
= 2cosacosb
RHS
thanks
====================================
==================================
We know that
cos( a - b ) = cosacosb + sinasinb
cos( a + b ) = cosacosb - sinasinb
now
RHS
cos ( a - b ) + cos ( a + b )
cosacosb + sinasinb + cosacosb - sinasinb
= cosacosb + cosacosb
= 2cosacosb
RHS
thanks
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vishalkumar6:
thanks
i knew the answer dude but i know the pleasure of getting a thanks
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