A2 June 2025 Paper 2 Q1

1 The vectors \(\begin{bmatrix} a \\ b \end{bmatrix}\) and \(\begin{bmatrix} c \\ 1 \end{bmatrix}\) are perpendicular.

Which one of the following statements must be true?

Tick (✓) one box. [1 mark]

• \(a = bc\)
• \(b = ac\)
• \(a = -bc\)
• \(b = -ac\)