Skill: Find missing side lengths from perimeter

Perimeter is the total distance around a shape. To find a missing side:

1. Add the known side lengths.
2. Subtract that sum from the perimeter.
3. Check that all side lengths add to the given perimeter.

Example: A polygon has a perimeter of $(32)$ cm. Four sides measure $6$ cm, $8$ cm, $5$ cm, and $7$ cm. The fifth side is $x$ cm. Find $x$.

Write an equation using the perimeter:

$$6+8+5+7+x=32$$

First, add the known side lengths:

$$6+8+5+7=26$$

Now subtract $(26)$ from the total perimeter:

$$x=32-26$$ $$x=6\text{ cm}$$

So, the missing side length is $6$ cm.

Check:

$$6+8+5+7+6=32\text{ cm}$$

The total is $(32)$ cm, so the answer is correct. Remember, perimeter measures the distance around a shape, not the space inside it.