Question

ve that
) cos (n + 2)x cos (n + 1)x + sin (n + 2)x sin (n + 1)x = cos x​

Answer 1

Answer:

Step-by-step explanation:

cos(n+2-n-1)x       {cosAcosB+sinAsinB=cos(A-B)}-this is the formula

cosx =rhs

proved