Obtuse-Angled Triangles Count
CAT 2008 Slot 1 · QA · Medium · Geometry
Consider obtuse-angled triangles with sides , and . If is an integer, then how many such triangles exist?
- A.
5
- B.
21
- C.
10
- D.
15
- E.
14
Answer
C
Explanation
By triangle inequality, .
For the triangle to be obtuse, the square of the longest side must be strictly greater than the sum of squares of the other two sides.
Case 1: is the longest side (): Since , integer values of can be . Total = 5 values.
Case 2: is the longest side (): Since , integer values of can be . Total = 5 values.
Total possible integer values for .
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