Because you can just simplify to have 1-2 terms only. Eg:
13+2y+4y (this is a trinomial as it has 3 terms) can be simplified to just give 13+6y
By definition, we have to:
In plane geometry, a rectangle is a parallelogram whose four sides are at right angles to each other. Opposite sides have the same length.
There is a proof that a quadrilateral is a rectangle:
1) Its parallel sides are the same.
2) Its two diagonals are the same, and they bisect each other at the common midpoint
3) Any rectangle can be inscribed in a circle, two of whose diameters coincide with the diagonals of the rectangle.
4) If all the angles of a quadrilateral are right angles, then it is a rectangle
-28 because if you add 8 to -120 you get -112 then divide it by 4 and you got -28
