The points $(4, 0)$ and $(-4, 0)$ are two non-consecutive vertices of a rhombus with an area of $80$ square units. One of the other vertices is $(0, K)$ where $K > 0$. What is the value of $K$?
The area of a rhombus =
(1/2) product of the diagonal lengths
One diagonal length is 8.....so the other must be 20
And the mid-point of this diagonal is at the origin
So.....(0,10) and (0, -10) are the other two vertices
So....K must be 10