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What is the spherical building at the junction of Qiyang and Ningjingyan Expressway?

Area of inner circle:

3. 14×(20÷2) 2

=3. 14× 100

=3 14 (m2)

Outer circular area:

3. 14×(30÷2) 2

=3. 14×225

=706.5 square meters

Increased area:

706.5-314 = 392.5m2.

A: At this time, the flower bed area increased by 392.5 square meters.