Topic 9 of 11 · Form 3
Vectors and transformations
Column vectors; addition, subtraction and multiplication by a scalar; magnitude |(x, y)| = √(x² + y²); position vectors; vector geometry (showing points are collinear or lines parallel).
Notes for this topic 1 file, in order
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Vectors
Column vectors; addition, subtraction and multiplication by a scalar; magnitude |(x, y)| = √(x² + y²); position vectors; vector geometry (showing points are collinear or lines parallel).
Worked example: a = (3, −4). Find |a| and 2a.
|a| = 5; 2a = (6, −8)
Worked example: OA = a, OB = b, and M is the midpoint of AB. Express OM in terms of a and b.
AB = b − a → OM = a + ½(b − a) = ½(a + b)
Transformations
- Reflection (state the mirror line), rotation (centre, angle, direction), translation (vector), enlargement (centre and scale factor, including fractional and negative factors).
- Describe a single transformation fully.
- Combined transformations.
Enlargement
Lengths multiply by the scale factor k; areas by k². A negative scale factor inverts the image through the centre.
Check yourself
- Find the magnitude of (5, 12).
- Describe the transformation mapping (2, 3) to (3, 2) for every point.
- A shape of area 6 cm² is enlarged by scale factor 3. Find the new area.
Show answers
- 13
- Reflection in the line y = x.
- 54 cm²
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