A QuiltPlan piecing reference
Half-Rectangle Triangles
one pieced pair, two mirrored units
A half-rectangle triangle can't be rotated to flip its diagonal the way a half-square triangle can. So every HRT pattern needs a matched forward and backward pair. Cut both rectangles the same size; the method below makes one of each in a single pass.
Get the ¼″ marks right
Come in ¼″ along both edges from the true corner (the ×): where those two measurements meet is your mark, not the corner itself. Do the same at the opposite corner, then pin the two marks together in the next step, and the rectangles land crossed at an angle instead of stacked square.
1 · Mark
Mark ¼″ points on both rectangles; draw the diagonal on fabric B.
2 · Pin
Lay B right-side-down on A, aligning the ¼″ marks: the layers cross at an angle, not stacked square.
3 · Sew & cut
Stitch a scant ¼″ on both sides of the line, then cut apart on the drawn diagonal.
4 · Result
Press open for two mirrored HRT units: one forward, one backward.
Forward
Mark top-left ↔ bottom-right.
Backward
Mark top-right ↔ bottom-left.
Cut a rectangle pair for each direction and run the method once per pair. An HST can rotate to flip its diagonal; an HRT can't. Piecing one of each keeps your points aimed the right way.
Cut both rectangles the same size: any ratio works, not just 5″×7½″.
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