Theory:

A triangle has \(3\) sides, \(3\) vertices, and \(3\) angles. A triangle whose vertices \(A\), \(B\), and \(C\) referred to \(△ABC\).
 
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Properties of a triangle:
The first property of a triangle: \(180°\) is always the sum of the three interior angles of a triangle.
 
triangle(1).PNG
 
The three angles of the \(△ABC\) are \(∠A\), \(∠B\), and \(∠C\).
 
As per the property, the sum of the three angles of the \(△ABC\) is \(180°\).
 
That is, \(∠A + ∠B + ∠C = 180°\).
The second property of a triangle: The sum of the length of a triangle's two sides is always greater than the length of the triangle's third side.
triangle(2).PNG
 
The three sides of the \(△ABC\) are \(AB\), \(BC\) and \(AC\).
 
As per the property, the sum of the length of any two sides of an \(△ABC\) is always greater than the length of the third side of the \(△ABC\).
 
Let the two sides are \(AB\) and \(BC\), and the third side is \(AC\).
 
Thus, we have \(AB + BC > AC\).
 
Similarly,
 
\(BC + AC > AB\) or
 
\(AB + AC > BC\).