The Shulbasutras of Baudhayana, Apastamba, Katyayana and Manava: With Text, English Translation and Commentary c8.t8.16

c8.t8.16

*The wings* : A rectangle *ABCD*, of which *AB* is 150 *aṅg*. and *BC* 180 *aṅg.*, is formed (Fig. 38 (d)). At the mid-point *P* of *BC* a perpendicular *PE* is drawn towards east so that *PE* is 90 *aṅg*. Then the triangle *EBC* is cut off and placed on the eastern side *AD* as the triangle *FAD*. The area of the figure *ABECDF* remains the same as the rectangle *ABCD*. In this way the wing is bent or curved (*nirṇāma*). That the area is not affected by bending in this way is clearly recognized in the *Śatapatha Brāhmaṇa* : "He then makes the wings crooked, for a bird's wings are crooked.........he thus draws them out by just as much as he draws them in; and thus, indeed, he neither exceeds (its size) nor does he make it too small."a