Answer:
The length of the longer side is 28 meters
Step-by-step explanation:
we know that
In a parallelogram, the intersecting diagonals bisect each other;
The supplementary angle of 60° is 120°.
see the attached figure to better understand the problem
Let
a ----> the length of the longer side
b ----> the length of the shorter side.
Apply the Law of Cosines to the lower triangle.
[tex]a^2 = 20^2 + 12^2 - 2(20)(12) cos(120\°)[/tex]
[tex]a^2 = 784[/tex]
[tex]a=28\ m[/tex]
therefore
The length of the longer side is 28 meters
