Heya!
Question #15:
To find the perimeter of the object, you can count the amount of squares that are on the outside of the object. After you country all around the object, the perimeters is 22 units (Option D)
Question #16:
Since we know the total perimeter, we can divide by the amount of sides a hexagon has because all of the sides are the same length. A hexagon has 6 sides. 42 / 6 = 7 inches (Option A)
Question #17:
To calculate the perimeter of the rectangle, you can add all the sides together. First, find common denominators.
6 1/2 = 6 2/4 and 3 1/4
Now, add all the sides together.
6 2/4 + 6 2/4 + 3 1/4 + 3 1/4 = 19 1/2 cm (Option B)
Question #18:
We can find the perimeter of the semi circle and square separately. Only take the perimeter of the square using 3 sides since the fourth sides is in the semi circle.
8 + 8 + 8 = 24 inches
Circumference of a semi circle formula: C = πd
C = (3.14)(8)
C = 25.12
Now, add both perimeters together.
24 + 25.12 = 49.12 inches (Option D)
Best of Luck!