Answer :
Area between two consecutive ribs
= \(\frac{1}{8}^{th} \) times the Total Area of the umbrella
\( = \ \frac{1}{8} \ × \pi r^2 \) ,where \( r \ = \ 45 \)cm
\( = \ \frac{1}{8} \ × \ \frac{22}{7} \ × \ (45)^2 \ = \ \frac{22275}{28} \) cm2