Physics · MOTION IN A PLANE

Two vectors \( \mathbf{A} \) and \( \mathbf{B} \) have magnitudes of \( 9\text{ units} \) and \( 12\text{ units} \) respectively and act at right angles to each other. The magnitude of their vector sum \( \mathbf{A} + \mathbf{B} \) is:

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Correct answer · Option B

\( 15\text{ units} \)

For perpendicular vectors (\( \theta = 90^\circ \)), \( R = \sqrt{A^2 + B^2} = \sqrt{9^2 + 12^2} = \sqrt{81 + 144} = 15\text{ units} \).