1. If \(ABC\) is a triangle of sides \(AB =\) 15 \(cm\), \(BC =\) 17 \(cm\) and \(CA =\) 20 \(cm\), then find the semi-perimeter.
Semi-perimeter \(=\) \(cm\).
2. If \(ABC\) is a triangle of sides \(AB =\) 13 \(m\), \(BC =\) 17 \(m\) and semi-perimeter \(=\) 23 \(m\), then find the missing side of the triangle.
\(CA =\) \(m\).