Mathematics for IGCSE & O level - Vectors (Section 1 - No. 22)
In a regular hexagon ABCDEF, if \(\vec{OA} = \vec{a}\) and \(\vec{OB} = \vec{b}\), which of the following represents \(\vec{OD}\)?
\(\vec{a} + \vec{b}\)
\(2\vec{b} - \vec{a}\)
\(- \vec{a} - \vec{b}\)
\(2\vec{a} + \vec{b}\)
คำอธิบาย
OD = -OA + -AB = -a + - (b-a) = -a-b