Its area is 3. 14×( 1.2÷2)? ÷ 2+1.5×1.2 = 2.3652 ≈ 2.4 m2.

It costs 2.4×35×4=336 yuan to make four windows.

Figure ii

The shadow area is 3. 14× 10? (1+4) = 62.8cm2.

The area of the small circle is 62.8(2/5)= 157 cm2.

Figure 3

The perimeter of the shaded part is 3.14× 5+3.14× 2+3× 2 = 27.98 cm.

Shadow area is 3. 14×(5? -2? ) ÷2=32.97 square centimeters

Figure 4

The perimeter of the shaded part is 4× 2+3.14× 4÷ 2 =14.28 cm.

The shadow area is 4×4-3. 14×4? 4=3.44 square centimeters