Answer: The greenhouse covers an area of 126 square meters.

(2)[3. 14×6×2 1+3. 14×(6÷2)2×2]÷2,

=(395.64+3. 14×9×2)÷2,

=(395.64+56.52)÷2,

=452. 16÷2,

=226.08 (m2);

A: At least 226.08 square meters of plastic film is needed.