Question

1) The value of cosa x + COS? y - 2005 X x Cos y x cos(x + y) is
(a) sin (x + y)
(b) sin? (x + y )
(c) SS (x + y)
() sin4 (x + y) ​

Answer 1

Answer:

a) is the right answer that I now

Answer 2

Step-by-step explanation:

a^(2)-1``b^(2)-1``( 1)/(2)(a^(2)+b^(2)-2)``(1)/(2)(a^(2)+b^(2))` CGiven sin x +sin y = a and cos x +cos y = b ...