The edges of a plot of land are bordered on all sides by a forest forming a triangular plot. the edges of the plot of land are 35 m, 52 m, and 82 m. what are the angles of the border of the plot of land?

You can solve for sides of a triangle using the following equation. 

A = arccos (b^2 + c^2 - a^2/2bc)

And likewise for other variables by moving the letters. 

Ultimately, in this problem you get the following angle measures:

15.87
23.97
140.16