can you explain pls

Use basic identities to simplify sing a + cosa sinx. Enclose arguments of functions in parentheses. For example, sin (2x). Remember that writing sin(x) to the fourth power as sin" (a) is just a mathematical shorthand. You should write it as (sin (x) )4, which is what Mobius expects. sin (a) sin3 x + cos2 x sin x