SANKVAGRA AND EQUINOCTIAL MIDDAY SHADOW Rsine of the (Sun's) declination and the earthsine for the desired time is (the Rsine of) the Sun's agrā (for that time). The earthsine multiplied by the radius and divided by (the Rsine of) the Sun's agrā is the Rsine of the latitude. That is Rsin (Sun's agrā) and Rsin = - ✓(Rsin 8) + ( earthsine )2, earthsine x R Rsin (Sun's agrā) where is the Sun's declination and the latitude of the place. These results easily follow from the triangle ACB in Fig. 8. A rule for the determination of the samkvagra: 54. The Rsine of the altitude for the desired time multi- plied by the Rsine of the latitude and divided by (the Rsine of) the colatitude is the sankvagra, which is always south (of the rising-setting line).¹ SA = Rsin a, AB 93 The sankvagra (of a heavenly body) is the distance of the projection of the heavenly body on the plane of the horizon from its rising- setting line. In Fig. 8, the line AB denotes the Sun's śaḥkvagra. The sank vagra is measured from the rising-setting line and is always to the south of that line. It is more commonly known a sankutala. In Fig. 8, we have sankvagra, śankvagra Rsin a Rcos which gives the formula stated in the text. (1) (2) LSAB 90⁰, and SBA 90⁰, where a denotes the altitude, and the latitude of the place. Therefore from the triangle SAB, we have Rsin 5 A rule for finding the equinoctial midday shadow: 55. Multiply the samkvagra by 12 and divide by the Rsine of the altitude: the result is (the length of) the equinoctial 1 This rule occurs also in A, iv. 29 and in LBh, iii. 16.
