Mathematics

Problem

The semi-perimeter of a triangle is

12\,\text{cm}

. Two of its sides measure

7\,\text{cm}

and

8\,\text{cm}

, and its area is

30\,\text{cm}^2

. The third side is a)

9\,\text{cm}

7.5\,\text{cm}

8.25\,\text{cm}

9.5\,\text{cm}