Answer :
[tex]c = \frac{ \alpha \times \pi }{180} \times r \\ \\ c = \frac{360\pi}{180} \times \frac{9}{10} \\ \\ c = \frac{18\pi}{10} \\ \\ c = 1.8 \times 3.142 \\ \\ c = 5.7[/tex]
Answer: 5.7 cm
Step-by-step explanation:
Circumference.= 2πr
= 2 x 3.142 x 0.9
= 5.7 cm.