3/8 inch is the height of one dog ear!!! So for the strip size for the easy angle ruler just remove the 3/8 inch from the square size that's supposed to be cut into 1/4's .
Formula for Area of a Triangle
The formula for half-square triangle quilt blocks.
The Primary Gal: Discovering the Formula for Area of a Triangle!
Area Formulas for Parallelograms, Triangles, & Trapezoids (6-8)
Formula for calculating size of triangles for a square-in-a square block
Quilt Block Patterns
Geometric Crocheted Shape Formulas, Works for Circles,Triangles, Squares and Hexagons | Scarlet Dash Blog
Crafty Needle & Thread
Alamosa Quilter: Half Square Triangle Formula Here is a simple formula for how to make half square triangles from squares.
Half-square Triangle...Tutorial and Maths Formulas for Quilting.