If a triangle ABC is right angled at C, then the value of \(\cos(A+B)\) is:
Answer: A
In any triangle, A + B + C = 180°.
Since the triangle is right-angled at C, we have C = 90°.
A + B + 90° = 180°
A + B = 90°.
Therefore, \(\cos(A+B) = \cos(90°) = 0\).