| 1835 - 684 pàgines
...180° - 6 6 > 90° A > 90° a > 180° - 6 The first is evident on inspection of r, i sin- A sm. В = sin. 6 sin. a as no sine can be > 1. The four last...shown to follow, from the formula cos. a — cos. ¿>. cos. с cos. A = ; — ; — г sm. 6 sin. с which, since sin. 6 and sin. с are positive (5)... | |
| Isaac Todhunter - 1863 - 182 pàgines
...limiting form of the proposed formula will be a relation in Plane Trigonometry. For example, in Art. 106, from the formula , cos a — cos b cos c cos A = - . — ; — r sin b sin c we deduce now suppose r to become infinite; then ultimately and this is the expression for... | |
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