2.1 Design of the Sine Quadrant
In the development of Islamic civilization and science in the Malay World, the sine quadrant tool is better known as
rubuc mujayyab. The word ‘rubuc’ means quadrant, while the word ‘mujayyab’ refers to grid point of sine ratio.
Thus [3], states that the sine quadrant is similar to an analog computer which can be used to solve trigonometric
equations. Physically, this tool consists of horizontal and vertical grids bound by two axes, the horizontal axis
(jaibul tamam) starting from the central quadrant up to the beginning of the curve (awal qaus) indicated as 0°. The
vertical axis (sittini) starting from the central quadrant until the end of the curve (akhir qaus) indicated by 90°. The
radius of the two axes is the radius of the quadrant, measuring 60 units (R = 60 units = 1 radius). The value of a
circular ‘chord’, R = 60 is the same value used in basic concepts of geometry and trigonometry since the Greek and
Hindu age and in Islamic civilization, as explain in [5]. The reading of the horizontal and vertical grids down from
the two axes is divided into sixty units, making its scale in units of sexagesimal.