Note to Fig. 9.
To inscribe a nonagon in a circle, वृत्तान्तर्गत नवभुजं i. e., to divide it into nine parts. “A circle being described as before, inscribe a triangle वृत्तान्तर्गत त्रिभुजं in it. Thus the circle is divided into three parts. Three equal chords समान पूर्णज्या being drawn in each of these portions, a nonagon is thus inscribed in it वृत्तस्य नव भुजक्षेत्रं; and three oblongs वृत्तस्य चतुर्भुज क्षेत्रं are formed within the same; of which the base is equal to the side of the (inscribed) triangle भूमिवृत्तस्य त्रिभुजभुजतुल्यं । Then two perpendiculars लम्बपातद्वयं being drawn in the oblong, it is divided into three portions, the first and last of which are triangles परपूर्ब्बांश त्रिभुजं; and the intermediate one is a tetragon. मध्यांश चतुर्भुजं । The base in each of them is a third part of the side of the inscribed triangle त्रिभुजवाहोस्त्रितीयांशः(?). It is the upright (of a rectangular triangle) जात्यत्रिभुजकोटि; the perpendicular is its side; and the square root of the sum of their squares भुजकोटिवर्गयोगमूलं is the hypotenuse कर्णः, and is the side of the nonagon नवभुजं.
“To find the perpendicular लम्बं, put an assumed chord कल्पितज्या equal to half the chord पूर्णज्यार्द्धं of the (inscribed) tetragon; find its arrow in the manner aforesaid, and subtract that from the arrow of the chord तत्रिभुजस्यशर of the (inscribed) triangle, the remainder is the perpendicular. लम्बपरिमाणं । Thus the perpendicular लम्बं comes out 21,989: it is the side of a rectangular triangle. The third part of the inscribed एकजात्य त्रिभुजं triangle is 34,641: it is the upright. कोटि । The square root of the sum of their squares वर्गयोग मूलं is 41,031: and is the side of the inscribed nonagon.” वृत्तस्यनवभुजं ।
