The Shulbasutras of Baudhayana, Apastamba, Katyayana and Manava: With Text, English Translation and Commentary c7.24

c7.24

If it is desired to transform a square into a double (isosceles) triangle (that is, rhombus), a rectangle twice as large as the square to be so transformed is made; a pole is fixed at the middle of its east side; two cords with their ties fastened to it (the pole) are stretched to the middle points of the southern and northern side (of the rectangle); portions lying outside the cords are cut off; thereby the (isosceles) triangle on the other side is explained.