Draw a line through from one corner to the opposite corner so that you have two triangles.
Label the sides of each triangle 1,2,3 and measure the length of each side.
Convert fractions to decimal if necessary, for instance:
2 & 5/16 = 2 + ( 5 / 16 ) = 2.3125
With the lengths for one triangle go to
tri-angle calculator
Click on
[ 1) 3 SIDES ]
Using the first triangle (on the left) as a reference,
[ INPUT SIDE 1-3 ] .
Click on
[ CALCULATE ] to find the corresponding angles.
Repeat for other triangle/s, side/s, etc.