Answer: the first option is the correct answer.
Explanation:
The perimeter of a plane figure is the distance around it. An octagon has 8 sides. The perimeter of the octagon would be
8 × length of each side
The length of the base of the right angle triangle formed is equal to half the length of each side of the octagon. Since the length of the base of the right angle triangle is 0.7 centimeters, the length if each side of the octagon would be
0.7 × 2 = 1.4 centimeters
Therefore, the perimeter of the octagon would be
1.4 × 8 = 11.2 cm