WAEC - Further Mathematics (2006 - No. 21)

The area of a sector of a circle is 3\(cm^{2}\). If the sector subtends an angle of 1.5 radians at the centre, calculate the radius of the circle.

1 cm

\(\sqrt{2}\) cm

2 cm

4 cm

The area of sector in radians = \(\frac{r^{2} \theta}{2}\)

\(3 cm^{2} = \frac{1.5 \times r^{2}}{2}\)

\(r^{2} = \frac{3 \times 2}{1.5} = 4\)

\(r = 2 cm\)