Half Rectangle Triangles (HRT) are like half square triangles but are made up of two rectangle triangle halves sewn together to recreate a rectangle.
This tutorial has diagrams and easy to follow instructions on creating [2] Half Rectangle blocks.
The PDF is for a 4 page file for you to print out at home. I would highly recommend that you print the file out double sided and onto 100gsm weight paper for added strength and durability.
The printed option is for 1 set of [2] doubled sided pages printed onto 100gsm weight paper. There is also an option to have the set sent WITHOUT holes punched, or WITH holes (4 holes) punched to fit into the 4 hole handmade board folder.