2. that diagonal length of the maximum square is the diameter of the circle,
∴ Square area S= 1.2? ÷2=0.72(m？ ) (square area = diagonal square ÷2).
3.( 1) Annular area = large circle area-small circle area
= 10? π-9? Pi?
= 19×3. 14=59.66(m？ )。
(2) Use large perimeter ÷ interval =20×3. 14÷0.4= 157, (closed graph, without adding 1).
4. Are the wooden pillars in the house? In the corner? At the midpoint of one side?
When the wooden column is at the midpoint, the area is a semicircle with a radius of 6m+two 1/4 circles with a radius of 4.5.
+2 1/4 circle with radius of 1.5,
Area =6? π÷2+(6- 1.5)? π×2× 1/4+(4.5-3)? π×2× 1/4 = 18π+ 10. 125π+ 1. 125π= 29.25π= 9 1.845(m？ )。