The sides of a triangle are 3 cm, 5 cm and 7 cm. Find the greatest angle of the triangle.

Explanation

To find the greatest angle of a triangle with sides measuring 3 cm, 5 cm, and 7 cm, we can use the cosine rule. The cosine rule states that for any triangle with sides \(a\), \(b\), and \(c\) opposite to angles \(A\), \(B\), and \(C\) respectively, the following relationships hold:

\[ \cos A = \frac{b^2 + c^2 - a^2}{2bc} \]
\[ \cos B = \frac{a^2 + c^2 - b^2}{2ac} \]
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