Parallelogram

Please see the attached PDF file. I would prefer a PDF file solution. Thank you! Not that the statement is of the "if and only if" type and so required proof of both directions. I would like someone other than OTA #103642 to provide a solution. Thanks!

Parallelogram

Please see attached PDF file. I would prefer a solution in PDF format. Thanks! Also I am looking for someone other than OTA #101767 OTA #103642 to reply. Thanks!

Algebraic series of complex numbers

Given an algebraic series with the following properties: The first term: a1=k-7i The difference: d=-1+2i The sum of the first n terms: S=-5+20i Find k

Pre-calc

Find all the solutions to 5(cos x)^2 - 4cosx-1=0

Find z all solutions

Please see the attached file for full problem description.