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ESO Y4B · Mathematics
Coordinate geometry · Coordinate geometry

Vectors in the plane

When a drone flies from one point to another, what matters is not just "where it starts" and "where it ends": what matters is the direction it has followed, how far it has moved horizontally and how far vertically. That information is stored by a new object: the vector.

Before you start, make sure you know: Pythagoras' theorem (2nd ESO)
Before you start, make sure you know: Plotting on the Cartesian plane (2nd ESO)

The vector as a displacement

Graph on the Cartesian plane of the fixed vector AB with initial point A(2, -1) and terminal point B(5, 3). A(2, −1) B(5, 3) AB = (3, 4)
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Given the points $A(2, -1)$ and $B(5, 3)$, calculate the components of vector $\vec{AB}$ and its magnitude.

Given the points $A(2, -1)$ and $B(5, 3)$, calculate the components of vector $\vec{AB}$ and its magnitude.

Solve
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Look at the vectors $\vec{u}$ and $\vec{v}$ represented on the grid. Write down their components and analytically calculate the coordinates of the sum vector…

Look at the vectors $\vec{u}$ and $\vec{v}$ represented on the grid. Write down their components and analytically calculate the coordinates of the sum vector $\vec{s} = \vec{u} + \vec{v}$.

u v
Solve

Magnitude of a vector

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Find the possible values of $x$ so that the vector $\vec{v} = (x, -8)$ has a magnitude exactly equal to $10$.

Find the possible values of $x$ so that the vector $\vec{v} = (x, -8)$ has a magnitude exactly equal to $10$.

Solve
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A delivery drone flies with its own velocity represented by the vector $\vec{v}d = (12, 5)$ km/h. At that instant, the wind blows with a velocity $\vec{v}v = (-3, 2)$…

A delivery drone flies with its own velocity represented by the vector $\vec{v}_d = (12, 5)$ km/h. At that instant, the wind blows with a velocity $\vec{v}_v = (-3, 2)$ km/h. Calculate the actual velocity vector of the drone and its speed (the magnitude of the resultant vector).

Solve

Parallel vectors

Graph on the Cartesian plane of two parallel vectors with different magnitudes and opposite senses. a = (6, −9) b = (−2, 3)
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State whether the vectors $\vec{a} = (6, -9)$ and $\vec{b} = (-2, 3)$ are parallel (have the same direction). Justify your answer mathematically.

State whether the vectors $\vec{a} = (6, -9)$ and $\vec{b} = (-2, 3)$ are parallel (have the same direction). Justify your answer mathematically.

Solve
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In the design of a bridge, three pillars must be perfectly collinear. On the architect's plan, the bases of the pillars are situated at the coordinates $P(-2, 1)$,…

In the design of a bridge, three pillars must be perfectly collinear. On the architect's plan, the bases of the pillars are situated at the coordinates $P(-2, 1)$, $Q(2, 3)$ and $R(8, k)$. Determine the value of $k$ so that they are correctly aligned.

Solve

The scalar product

Calculation of the scalar product of the vectors p(4, 5) and q(-2, 3), giving the number 7. p = (4, 5) q = (−2, 3) p · q = 4·(−2) + 5·3 = 7
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Calculate the scalar product of the vectors $\vec{p} = (4, 5)$ and $\vec{q} = (-2, 3)$. From the result, state whether they are perpendicular.

Calculate the scalar product of the vectors $\vec{p} = (4, 5)$ and $\vec{q} = (-2, 3)$. From the result, state whether they are perpendicular.

Solve

Perpendicularity and the scalar product

Graph of two perpendicular vectors p and q forming a right angle of 90 degrees. 90° p q
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Consider the vectors depending on a parameter $\vec{u} = (m, 2)$ and $\vec{v} = (3, m-1)$. Find the values of the parameter $m$ in two different geometric cases: a) So…

Consider the vectors depending on a parameter $\vec{u} = (m, 2)$ and $\vec{v} = (3, m-1)$. Find the values of the parameter $m$ in two different geometric cases:

  1. a) So that $\vec{u}$ and $\vec{v}$ are perpendicular.
  2. b) So that $\vec{u}$ and $\vec{v}$ are parallel.
Solve
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Find out whether the triangle formed by the telecommunication antennas located at coordinates $A(1, 2)$, $B(4, 6)$ and $C(9, -1)$ is a right-angled triangle. Use the…

Find out whether the triangle formed by the telecommunication antennas located at coordinates $A(1, 2)$, $B(4, 6)$ and $C(9, -1)$ is a right-angled triangle. Use the scalar product of the vectors that form its sides to justify your answer.

Solve

Back to the beginning: If a drone takes off from point $A$ and lands at $B$, the vector $\vec{AB}$ gives the heading through its horizontal and vertical components, while its magnitude $|\vec{AB}|$ measures the total distance travelled in a straight line.

Summary

See all the exercises in this section