Roberta,
I have a suggestion to enable you to figure this one out yourself.
Place a square piece of paper larger than the block on a table under the block.
Use your square up ruler to draw a square around the block onto the paper leaving enough for seams and saving your points.
Draw around the 'star' points as well onto the paper.
Move the block aside and you will see that you are going to use 2 different triangles for squaring up this block.
Cut out and add seam allowances to the two shapes you will need and you'll have the triangle sizes you have to cut.
Jan in VA