सिद्धान्तशिरोमणि: गणिताध्याय (भास्कराचार्य - ग्रहगणित, मध्यमाधिकार व स्पष्टाधिकार सटीक)

236
calculating the bhuja ω'M and Koti
CM; Bhuja and Koti being known,
and the shadow Cω' being drawn,
holding two rods whose lengths are
equal to the bhuja and Koti perpendi-
cular to each other, one extremity of
the bhuja-rod being held at ω' and
one extremity of the Koti-rod being
held at C, and the rods making a
right angle at M, then the bhuja-rod
determines the north-south direction
and the Koti-rod the East-West dire-
ction.
Fig. 36
Verse 10. The Bhuja is defined as the distance of the
extremity of the shadow from the east-west line where
the S'anku or gnomon is placed at the intersection of
Eω and NS. Koti = √(S² − b²) ∴ Koti will be in the
East-West direction. So Chayā-koti = K sin z cos a (7).
Comm. Easy.
Verse 11. The Chayākarṇa, K is equal to √(S² + 12²),
so that √(K² − 12²) = S or √[(K + 12) (K − 12)] = S.
Comm. Easy.
Verse 12. The S'anku is also called Nara or Nā.
The zenith-distance of the Sun at Noon when the Sun
is in ♈ is the latitude of the place, called pala or
Aksha; the altitude then is called lamba or colatitude.
Comm. The word S'anku we have previously used
for the gnomon. It is also used for the H cosine of
the zenith-distance and to differentiate it from the
previous S'anku called Dwādasāṅgul'a-S'anku or
twelve-unit-length S'anku, it is termed Mahā S'anku
and occasionally Iṣṭa-S'anku. Mahā S'anku or Iṣṭa
S'anku = H cos z (8). Thus in figure (37) ☉M =
H cos z. In the fig. where gn = gnomon, go = S