To find the value of X for each triangle, we use the fact that the perimeter is the sum of all sides. For each problem, subtract the known side lengths from the given perimeter to solve for X.
Let’s go one by one:
1) Perimeter = 16.3 u
Sides: x, 7.2, 2 → x + 7.2 + 2 = 16.3 → x = 16.3 - 9.2 =
7.1
2) Perimeter = 10.5 u
Sides: 4.5, 2, x → 4.5 + 2 + x = 10.5 → x = 10.5 - 6.5 =
4.0
3) Perimeter = 25.8 u
Sides: x, 10.8, 6 → x + 10.8 + 6 = 25.8 → x = 25.8 - 16.8 =
9.0
4) Perimeter = 22.4 u
Sides: x, 8, 9.4 → x + 8 + 9.4 = 22.4 → x = 22.4 - 17.4 =
5.0
5) Perimeter = 20.6 u
Sides: x, 8.6, 5 → x + 8.6 + 5 = 20.6 → x = 20.6 - 13.6 =
7.0
6) Perimeter = 13.8 u
Sides: 5, 5.8, x → 5 + 5.8 + x = 13.8 → x = 13.8 - 10.8 =
3.0
7) Perimeter = 15.7 u
Sides: x, 6.2, 3 → x + 6.2 + 3 = 15.7 → x = 15.7 - 9.2 =
6.5
8) Perimeter = 25.6 u
Sides: x, 7, 10.6 → x + 7 + 10.6 = 25.6 → x = 25.6 - 17.6 =
8.0
9) Perimeter = 20.9 u
Sides: x, 8, 8.9 → x + 8 + 8.9 = 20.9 → x = 20.9 - 16.9 =
4.0
10) Perimeter = 25.8 u
Sides: 9, 10.8, x → 9 + 10.8 + x = 25.8 → x = 25.8 - 19.8 =
6.0
11) Perimeter = 20.6 u
Sides: x, 8.6, 7 → x + 8.6 + 7 = 20.6 → x = 20.6 - 15.6 =
5.0
12) Perimeter = 12 u
Sides: 3, 5.0, x → 3 + 5.0 + x = 12 → x = 12 - 8.0 =
4.0
Final Answer:
1. 7.1
2. 4.0
3. 9.0
4. 5.0
5. 7.0
6. 3.0
7. 6.5
8. 8.0
9. 4.0
10. 6.0
11. 5.0
12. 4.0
Parent Tip: Review the logic above to help your child master the concept of perimeter of triangle worksheet.
