The surface area is the sum of all exposed surfaces, and the front and back, up and down, left and right areas are equal respectively.
Front and rear area:1x1x10x2 = 20cm2.
Left and right areas:1x1x10x2 = 20cm2.
Upper and lower areas:1x1x16x2 = 32cm2.
Surface area: 20+20+32=72 cm2.
Question 2: (1) trapezoidal area: (6+12) x9x1/2 = 81cm2.
(2) Because the area of triangle ADE is equal to the area of triangle CDF, let CF be x cm long.
9x* 1/2=6*6* 1/2
Solution: x=4
That is, CF is 4 cm long.
(3) BF = BC-CF = 12-4 = 8cm。
Trapezoidal ADFB area: (6+8) x9x 1/2 = 63cm2.
Triangle ADE area: 6x6x 1/2 = 18cm2.
BEF area of triangle: be = 9-6 = 3cm.
3x8x 1/2= 12 cm2
DEF area of triangle: 63- 18- 12 = 33cm2.