Let's solve the problem step by step.
We are given a composite shape made up of two rectangles, and we need to find the missing length marked with a question mark ("?").
Step 1: Understand the shape
The figure looks like an "L" shape composed of two rectangles:
- The
left vertical part is 6 cm tall and 3 cm wide.
- The
bottom horizontal part extends from the right side of the vertical part and is 3 cm high (same as the height of the lower rectangle).
- The total width of the entire shape at the bottom is 10 cm.
- The left part takes up 3 cm of that width, so the remaining horizontal length (the unknown "?") must be the rest.
---
Step 2: Find the missing horizontal length
Total bottom width = 10 cm
Width taken by the left vertical rectangle = 3 cm
So, the missing horizontal length (the base of the right rectangle) is:
$$
? = 10\,\text{cm} - 3\,\text{cm} = 7\,\text{cm}
$$
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Step 3: Verify the dimensions
Let’s check if this makes sense:
- The left vertical rectangle: 6 cm tall × 3 cm wide.
- The right horizontal rectangle: 3 cm tall × 7 cm wide.
- Together, they form the L-shape.
- The top edge of the whole shape:
- Left part: 3 cm wide.
- Then the horizontal part starts at 3 cm from the left and goes to 10 cm → 7 cm long.
- The total height on the left is 6 cm, but the right part is only 3 cm high — consistent with the L-shape.
✔ All dimensions match.
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✔ Final Answer:
$$
\boxed{7\,\text{cm}}
$$
The missing length is
7 cm.
Parent Tip: Review the logic above to help your child master the concept of perimeter with missing side.
