Find the perimeters of :
A triangle ABC having sides of lengths , AB=7 cm , BC =5 cm , AC = 8.5 cm

Answer

To find the perimeter of triangle ABC with the given side lengths, we can follow these steps:

### Step 1: Identify the lengths of the sides
We are given the lengths of the sides of triangle ABC:
- AB = 7 cm
- BC = 5 cm
- AC = 8.5 cm

### Step 2: Use the formula for the perimeter of a triangle
The formula to calculate the perimeter of a triangle is:
\[ \text{Perimeter} = AB + BC + AC \]

### Step 3: Substitute the values into the formula
Now, we substitute the values of the sides into the formula:
\[ \text{Perimeter} = 7 \, \text{cm} + 5 \, \text{cm} + 8.5 \, \text{cm} \]

### Step 4: Perform the addition
Now, we add the values together:
1. First, add AB and BC:
\[ 7 + 5 = 12 \, \text{cm} \]
2. Next, add the result to AC:
\[ 12 + 8.5 = 20.5 \, \text{cm} \]

### Step 5: State the final result
Thus, the perimeter of triangle ABC is:
\[ \text{Perimeter} = 20.5 \, \text{cm} \]

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