# Prove that As we know cos (x + y) = cos x cos y – sin x sin y

cos (x – y) = cos x cos y + sin x sin y

cos (x + y) + cos (x – y ) = 2 cos x cos y

So,  ] As we know cos(π -x) = - cos x = 0

= RHS

Hence proved

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos  Conditional Identities31 mins  Trigonometric Functions - 0568 mins  Trigonometric Functions - 0152 mins  Graphs of trigonometric ratios | Trigonometric Identities39 mins  Quiz on Graph of Trigonometric Ratios40 mins  Trigonometric Functions - 0366 mins  Trigonometric Functions - 0658 mins  Trigonometric Series45 mins  Interactive Quiz on trigonometric ratios & identities73 mins  Trigonometric Functions - 0268 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation view all courses 