Answer:
1. 172 cm²
2. 226.56 cm²
3. 336 cm²
4. 284 cm²
Step-by-step explanation:
which one ? all ?
a surface area of an object is always the sum of the individual shapes areas on its surface.
1. 6 rectangles (length×width)
2 rectangles of 2×8 = 16 cm²
32 cm²
2 rectangles of 2×7 = 14 cm²
28 cm²
2 rectangles of 7×8 = 56 cm²
112 cm²
total : 32+28+112 = 172 cm²
2. 2 triangles and 3 rectangles
2 triangles (baseline × height / 2) = 7.2×4.8/2 = 17.28 cm²
34.56 cm²
2 rectangles 10×6 = 60 cm²
120 cm²
1 rectangle 10×7.2 = 72 cm²
72 cm²
total : 34.56+120+72 = 226.56 cm²
3. 2 triangles (right-angled) and 3 rectangles
2 triangles (a×b/2) = 8×6/2 = 24 cm²
48 cm²
1 rectangle 6×12 = 72 cm²
72 cm²
1 rectangle 8×12 = 96 cm²
96 cm²
1 rectangle 10×12 = 120 cm²
120 cm²
total : 48+72+96+120 = 336 cm²
4. 6 rectangles
2 rectangles of 3×10 = 30 cm²
60 cm²
2 rectangles of 3×9 = 27 cm²
54 cm²
2 rectangles of 10×9 = 90 cm²
180 cm²
total : 60+54+180 = 294 cm²
