Explanation:
it is not stated but it has to be assumed that all angles in 4. are right angles (or multiples of 90° angles). otherwise the problems are not solvable.
the perimeter is the total way around the object one time. that means it is the sum of all side lengths.
4a.
10 - 3 = 7 m
12 - 3 = 9 m
12 + 10 + 3 + 7 + 9 + 3 = 44 m
4b.
5 - 2 = 3 cm
8 + 2 = 10 cm
10 + 5 + 8 + 3 + 2 + 2 = 30 cm
4c.
5 = 5 mm
7 = 7 mm
12 - 5 - 5 = 2 mm
12 + 5 + 5 + 7 + 2 + 7 + 5 + 5 = 48 mm
4d.
9 = 9 m
2 + 4 + 2 = 8 m
9 + 8 + 9 + 2 + 3 + 4 + 3 + 2 = 40 m
4e.
3 = 3 km
10 - 4 - 2 = 4 km
10 + 3 + 4 + 5 + 4 + 5 + 2 + 3 = 36 km
4f.
2 + 3 + 2 + 3 + 2 = 12 m
5 = 5 m
3 = 3 m
7 = 7 m
12 + 7 + 2 + 5 + 3 + 3 + 2 + 3 + 3 + 5 + 2 + 7 = 54 m
2a.
15 + 8 + 15 + 8 = 46 mm
2b.
7 + 12 + 16 + 9 = 44 cm
2c.
22 + 17 + 18 + 21 + 40 = 118 m
2d.
12 + 12 + 15 = 39 cm
2e.
6 equal sides.
41 × 6 = 246 cm
2f.
2 pairs of equal sides.
2×300 + 2×700 = 600 + 1400 = 2000 mm