Half-square triangles, or right triangles, can be quickly and accurately cut with a rotary cutter. Many quilts can be made with half-square triangles (two triangles cut from one square).
If you need to cut half-square triangles, our instructions will say something like this:
From light green print, cut:
2—4-7/8" squares, cutting each in half diagonally for 4 large triangles total
First cut the squares in the size specified in the instructions. Then line up a ruler’s edge with the opposite corners of the square. Cut along the ruler’s edge to cut the square in half diagonally; separate the triangles. Repeat with the remaining square. Because the triangles’ long edges are on the bias, avoid stretching them when piecing so you don’t distort the seams.