Let be a trapezoid such that , , and . Let and be the midpoints of and , respectively. If , find the area of the trapezoid .
Problem 1341
Official solution
1. Identify the given information and construct the necessary points:
- Trapezoid with .
- Diagonals and with lengths and .
- Midpoints and of and respectively, with .
2. **Construct parallelograms and :**
- Extend and to form parallelograms and .
- Since and are midpoints, is parallel to both and .
3. Analyze the properties of the trapezoid and the midsegment:
- The midsegment of a trapezoid is parallel to the bases and its length is the average of the lengths of the bases.
- Let and . Then, .
4. **Use the given length of the midsegment to find the relationship between and :**
- Given , we have:
5. Determine the height of the trapezoid using the diagonals:
- Since , the diagonals intersect at right angles.
- The area of the trapezoid can be found using the formula for the area of a right-angled triangle formed by the diagonals:
6. Verify the area calculation:
- The area of the trapezoid is indeed given by the product of the diagonals divided by 2, confirming the calculation.
The final answer is .