The martins swimming pool is a square and is in the center of a square plot that is 33 meters on a side. they have 1008 square meters of lawn. how long is a side of the pool?

Me ! write an equation for the interior angles of this triangle that uses the triangle sum theorem

Find the perimeter of the triangle with vertices  d(3, 4),  e(8, 7), and  f(5, 9). do not round before calculating the perimeter. after calculating the perimeter, round your answer to the nearest tenth.  

How is this equation completed? i cannot find any examples in the book.