In $$\triangle ABC, \angle A = 90^\circ, AB = 20$$ cm and BC = 29 cm. What is the value of $$(\sin B - \cot C)$$?

A

$$-\frac{9}{29}$$

B

$$-\frac{189}{580}$$

C

$$\frac{189}{580}$$

D

$$\frac{9}{29}$$