「數學」- 圖形面積及周界

1) 周界
= 4+7+10+2
= 23 (cm)
面積
= (4 x 7) + [2 x (10-4)]
= 28 + 12
= 40 cm^2

2) 周界
= (8 x 2 x 3.14)/2 + [8 + 8 + (2 x 8)]
= 25.12 + 32
= 57.12 (cm)

面積
= (8^2 x 3.14)/2 + (8 x 8 x 2)
= 100.48 + 32
= 132.48 (cm^2)

[4x(7-2)]x(10x2)
=[4x5]x20
=20x20
=400cm2