Published by:
CGP EDU Academic Team
Published on: August 12, 2026
Show that : cos² α + cos² ( α + β ) − 2cos α cos β cos ( α + β ) = sin² β .
Text Solution
Verified by ExpertsThe correct answer is:
CHECK THE SOLUTION.
LHS = cos 2 α + cos( α + β ) { cos α cos β – sin α sin β – 2 cos α cos β }
= cos2 α – cos ( α + β ) . cos ( α – β ) = cos 2 α – cos 2 α + sin 2 β = sin 2 β = RHS
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