Type of Triangle

Write a query identifying the type of each record in the TRIANGLES table using its three side lengths. Output one of the following statements for each record in the table:

• Equilateral: It’s a triangle with 3 sides of equal length.
• Isosceles: It’s a triangle with 2 sides of equal length.
• Scalene: It’s a triangle with 3 sides of differing lengths.
• Not A Triangle: The given values of A, B, and C don’t form a triangle.

Input Format

The TRIANGLES table is described as follows:

Each row in the table denotes the lengths of each of a triangle’s three sides.

Sample Input

Sample Output

Isosceles
Equilateral
Scalene
Not A Triangle

Explanation

Values in the tuple (20,20,23) form an Isosceles triangle, because A ≡ B.
Values in the tuple (20,20,20) form an Equilateral triangle, because A ≡ B ≡ C. Values in the tuple (20,21,22) form a Scalene triangle, because A≠B≠C.
Values in the tuple (13,14,30) cannot form a triangle because the combined value of sides A and B is not larger than that of side C.

Solution Implementation

SELECT CASE
WHEN A + B <= C OR A + C <= B OR B + C <= A THEN 'Not A Triangle'
WHEN A = B AND B = C THEN 'Equilateral'
WHEN A = B OR B = C OR A = C THEN 'Isosceles'
ELSE 'Scalene'
END
FROM TRIANGLES;