If D and E are respectively the midpoints of the sides AB and BC of `triangle ABC ` in which AB = 7.2 cm, BC = 9.8 cm and AC = 3.6 cm then determine the length of DE.

Explanation

To find the length of segment DE in triangle ABC, where D and E are the midpoints of sides AB and BC respectively, we can use the Midpoint Theorem. Here’s a step-by-step solution:

### Step 1: Identify the midpoints
- D is the midpoint of side AB.
- E is the midpoint of side BC.

### Step 2: Write down the lengths of the sides
- AB = 7.2 cm
- BC = 9.8 cm
- AC = 3.6 cm

### Step 3: Apply the Midpoint Theorem
According to the Midpoint Theorem, the segment joining the midpoints of two sides of a triangle is parallel to the third side and is half the length of the third side.

### Step 4: Determine the length of DE
Since DE is the segment joining the midpoints D and E:
- DE is parallel to side AC.
- Therefore, DE = 1/2 * AC.

### Step 5: Calculate DE
- AC = 3.6 cm
- DE = 1/2 * 3.6 cm = 1.8 cm

### Conclusion
The length of DE is 1.8 cm.

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