A \(60\,\text{m}\) rope will be used at full length to mark the perimeter of a right triangle. All three side lengths, \(a\), \(b\), and \(c\), must be whole numbers of meters.
Find two different sets of side lengths and show that each set forms a right triangle.
Hints
- Recall a simple whole-number triple that satisfies the Pythagorean theorem.
- Scaling all three sides of a right triangle by the same factor preserves the right angle.
- The three side lengths must add to exactly \(60\).
Solution
1. A scaled \((3, 4, 5)\) triangle can have perimeter \(60\,\text{m}\). Since \(3+4+5=12\) and \(60\div12=5\), scaling each side by \(5\) gives \(15\), \(20\), and \(25\). The perimeter is \(60\), and \(15^2+20^2=225+400=625=25^2\).
2. A scaled \((5, 12, 13)\) triangle also works. Since \(5+12+13=30\) and \(60\div30=2\), scaling each side by \(2\) gives \(10\), \(24\), and \(26\). The perimeter is \(60\), and \(10^2+24^2=100+576=676=26^2\).
Answer
1. \(15\,\text{m}, 20\,\text{m}, 25\,\text{m}\), because \(15+20+25=60\) and \(15^2+20^2=25^2\).
2. \(10\,\text{m}, 24\,\text{m}, 26\,\text{m}\), because \(10+24+26=60\) and \(10^2+24^2=26^2\).