Invalid expression. When calling...

I have a code that says

Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters.

when i am trying to type cos^2(x/2). Also, i have defined x as pi/6.

Answer 1

[Walter Roberson]

cos(x/2)^2

[Liam Sullivan]

thank you