How do I sew triangle on to rectangle? Help please
 

I want to add a triangle to the ends to make a rectangle...and for the life of me I can not figure out what size to cut these. I am attaching a drawing I made. The finished width is 7" - each finished triangle will be 2 1/2" x 2". Can someone give me the dimensions of the 3 pieces I need to cut. The finished sizes are shown on the drawing too. I am ready to pull out all my hair! Thanks!

you make squares (I'm assuming 2 1/2 inches) and lay them face down on the corners of your piece. sew a line diagonally and fold back and press. then trim the inner square fabric out if you like. no triangles to sew with that way. Looking at your drawing, maybe a 2 1/2 inch by 2 inch piece on each corner.

These snowballs won't be squares, but will look more like kites in their shape.
The graphic below was drawn for another project be still will work for yours; just turn the kite shape so the short side is along the bottom rather than the long side being along the bottom.

Jan in VA

LOL! I used my Paint program to draw up a little tutorial and once I posted it I realized it wouldn't work for triangles. The method I was describing only works with squares. :o (So, I quickly deleted my post.) Jan's suggestion looks great! If I hadn't seen her solution I probably would have paper pieced it as a last resort :p

Sorry Jan...I don't get this either. What size are the pieces?

Okay, sorry I just saw that this was not clear.
On the kite shape, make the longer side be 2.5".
Make the short side be 2".
From point to point (where I marked the 90 degree circle) measure approximately 3.25"
You'll have to play a bit by folding a piece of paper in HALF then cutting into a kite shape -- sort of like we used to cut out hearts and snowflakes as kids.

Remember to make that angle between the 2.5" and the 2" sides be 90 degrees, a right angle.

Jan in VA

You are working too hard. Copy your drawing and paper piece it.

I have never done paper piecing either! I have done a lot of applique quilts...trying out new techniques.

Cut a pair of 2 1/2 by 3 inch rectangles, then sew them to the ends of your 3 by 7 1/2 inch rectangle from corner to corner of the small rectangle.

I must not have been very clear with my information. The drawing I show has the FINISHED sizes shown. When I follow your directions, and some of the others ...it comes out too small. When I add a 1/2" to each piece it comes out too long. and the triangle is not equal to the rectangle.

I really appreciate all the attempts! Maybe I am just not following the directions right. I will try again today to see why this isn't working for me.