Show that cos 2x cos x/2 - cos 3x cos 9x/2 = sin 5x sin 5x/2

[@onlycringeshort4848]

Sir jii love uuu

[@akhilgupta3079]

Sir done very good explanation 👍👍

[@DeekshithaNagaraj]

You are " the best "😍

[@sanskarrathorevitha5050]

Very helpful video sir 🥰

[@yashchauhan1929]

Done sir 🙏🏻🙌

[@yogitadahiya7347]

Done sir

[@RamrajYadav-tf9nw]

How are you