Prove that
(i) 
(ii) 
(iii) 
(i)
………[Using –2sinx.siny = cos(x + y)–cos (x–y)]
(ii)
………..[using 2cosx.cosy = cos(x + y) + cos(x–y)]
(iii)
...[Using2sinx.cosy = sin(x + y) + sin(x–y)]
1
Prove that
(i)
(ii)
(iii)
(i)
………[Using –2sinx.siny = cos(x + y)–cos (x–y)]
(ii)
………..[using 2cosx.cosy = cos(x + y) + cos(x–y)]
(iii)
...[Using2sinx.cosy = sin(x + y) + sin(x–y)]