In the Writer window, write the following formulae using Mark up.
(Use Elements window if necessary)

1) Summation of x to the power of 2
2) Sin to the power of x plus cos to the power of x = 1 (use the Functions category in the Elements window)
3)Summation from 1 to n of x. (use the Operators category to set the limits for summation)
4)Change font to Arial and size to 18 point
5)Provide more spacing between the symbols.