Hi, I'm very new to programming, this being my second program. I've been working on this and I still can't seem to get this last section to work. I'm supposed to use a programmer defined function to solve for the area of the rectangle for an integral but I cant get past the line where it has the equation. The message it says is "invalid operands of types `double ()(double)' and `double ()(double)' to binary `operator*'. I looked it up online and couldnt find anything to really tell me what was wrong other than it's typically something simple to fix which makes me feel programming retarded lol. Any help will be appreciated!!
Here is the part of my program that keeps messing up.\
double area (double low_x, double high_x, double delta_x);
y = ((cos * cos) (low_x)) + ((cos * cos)(low_x * low_x));
rect_area = (y * delta_x);
printf("rectangle area is: %lf", y);