The number of acute angled triangles whose sides are three consecutive positive integers and whose perimeter is at most 100 is
Question and options
The number of acute angled triangles whose sides are three consecutive positive integers and whose perimeter is at most 100 is
- 28
- 29
- 31
- 33
Answer and explanation
Correct answer: B - 29
Sides n-1,n,n+1; acute iff (n+1)^2<(n-1)^2+n^2, i.e. n^2>4n, n>4 (n=4 gives right triangle 3,4,5). Perimeter 3n<=100 gives n<=33. n=5..33: 29 triangles.
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