New
New
Year 11
Higher

Dividing vectors into ratios

I can solve geometric problems in 2D where vectors are divided in a given ratio.

New
New
Year 11
Higher

Dividing vectors into ratios

I can solve geometric problems in 2D where vectors are divided in a given ratio.

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Lesson details

Key learning points

  1. A vector can be divided into parts using a ratio.
  2. By converting the ratio to a fraction, you can express each part in terms of the original vector.
  3. This allows you to perform further manipulations.

Keywords

  • Vector - A vector can be used to describe a translation.

  • Displacement - Displacement is the distance from the starting point when measured in a straight line.

  • Resultant vector - A resultant vector is the single vector that produces the same effect as a combination of other vectors.

Common misconception

When calculating the resultant vector, pupils can incorrectly sum vectors due to opposite directions or proportions of vectors.

Encourage pupils to write a clear vector pathway, sometimes using highlighters can help visualise this pathway.

Give pupils opportunities to form vector pathways first, before calculating the fractional algebraic vector. Once pupils understand how to form multiple different pathways for the same resultant vector, move on to calculating these in algebraic form.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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6 Questions

Q1.
Work out the resultant vector for $${10 \choose -2} + {4 \choose 9}$$.
$${2 \choose 7}$$
Correct answer: $${14 \choose 7}$$
$${5\choose 7}$$
$${9\choose 7}$$
Q2.
Match each notation to its correct meaning.
Correct Answer:$$\overrightarrow{OX}$$ ,A vector starting from $$O$$ and ending at $$X$$

A vector starting from $$O$$ and ending at $$X$$

Correct Answer:$$OX$$,A line segment with points $$O$$ and $$X$$ at each end

A line segment with points $$O$$ and $$X$$ at each end

Correct Answer:$$\overrightarrow{XO}$$ ,A vector starting from $$X$$ and ending at $$O$$

A vector starting from $$X$$ and ending at $$O$$

Correct Answer:$$\overrightarrow{XY}$$ ,A vector starting from $$X$$ and ending at $$Y$$

A vector starting from $$X$$ and ending at $$Y$$

Correct Answer:$$XY$$ ,A line segment with points $$X$$ and $$Y$$ at each end

A line segment with points $$X$$ and $$Y$$ at each end

Q3.
Match each vector to an equivalent vector statement.
Correct Answer:$${12 \choose -9}$$,$$3\times {4 \choose -3}$$

$$3\times {4 \choose -3}$$

Correct Answer:$${16 \choose -12}$$,$$4\times {4 \choose -3}$$

$$4\times {4 \choose -3}$$

Correct Answer:$${-18 \choose -6}$$,$$2\times {-9 \choose -3}$$

$$2\times {-9 \choose -3}$$

Correct Answer:$${4\choose -20}$$,$$-2\times {-2 \choose 10}$$

$$-2\times {-2 \choose 10}$$

Correct Answer:$${-27\choose -27}$$,$$-3\times {9 \choose 9}$$

$$-3\times {9 \choose 9}$$

Q4.
Match each vector statement to an equivalent vector statement.
Correct Answer:$$5\mathbf{a}+2\mathbf{b}$$,$$\frac{1}{2}(10\mathbf{a}+4\mathbf{b})$$

$$\frac{1}{2}(10\mathbf{a}+4\mathbf{b})$$

Correct Answer:$$4\mathbf{a}+2\mathbf{b}$$,$$\frac{1}{3}(12\mathbf{a}+6\mathbf{b})$$

$$\frac{1}{3}(12\mathbf{a}+6\mathbf{b})$$

Correct Answer:$$2\mathbf{a}+3\mathbf{b}$$,$$\frac{1}{5}(10\mathbf{a}+15\mathbf{b})$$

$$\frac{1}{5}(10\mathbf{a}+15\mathbf{b})$$

Correct Answer:$$5\mathbf{a}-2\mathbf{b}$$,$$\frac{1}{2}(10\mathbf{a}-4\mathbf{b})$$

$$\frac{1}{2}(10\mathbf{a}-4\mathbf{b})$$

Correct Answer:$$15\mathbf{a}-12\mathbf{b}$$,$$\frac{3}{4}(20\mathbf{a}-16\mathbf{b})$$

$$\frac{3}{4}(20\mathbf{a}-16\mathbf{b})$$

Q5.
Select the vector path for $$\overrightarrow{AD}$$.
An image in a quiz
$$\overrightarrow{AB}+\overrightarrow{BC}+\overrightarrow{CD}$$
Correct answer: $$-\overrightarrow{AB}+\overrightarrow{BC}+\overrightarrow{CD}$$
$$\overrightarrow{AB}+\overrightarrow{BC}-\overrightarrow{CD}$$
Q6.
Select the statements which are true.
An image in a quiz
Correct answer: $$\frac{1}{2}\overrightarrow{IH}=\overrightarrow{CD}$$
Correct answer: $$2\overrightarrow{CD}=\overrightarrow{IH}$$
$$-\overrightarrow{IH}=\overrightarrow{HG}$$
$$-\overrightarrow{AB}=\overrightarrow{FE}$$
Correct answer: $$\frac{1}{2}\overrightarrow{FE}=\overrightarrow{BC}$$

6 Questions

Q1.
X is a point on a line AB. Match each vector statement to the correct ratio.
Correct Answer:$$AX:XB \; \text{is} \; 1:4$$,$$\frac{1}{5}\overrightarrow{AB}=\overrightarrow{AX}$$

$$\frac{1}{5}\overrightarrow{AB}=\overrightarrow{AX}$$

Correct Answer:$$AX:XB \; \text{is} \; 1:3$$,$$\frac{1}{4}\overrightarrow{AB}=\overrightarrow{AX}$$

$$\frac{1}{4}\overrightarrow{AB}=\overrightarrow{AX}$$

Correct Answer:$$AX:XB \; \text{is} \; 1:1$$,$$\frac{1}{2}\overrightarrow{AB}=\overrightarrow{AX}$$

$$\frac{1}{2}\overrightarrow{AB}=\overrightarrow{AX}$$

Correct Answer:$$AX:XB \; \text{is} \; 4 : 1$$,$$\frac{4}{5}\overrightarrow{AB}=\overrightarrow{AX}$$

$$\frac{4}{5}\overrightarrow{AB}=\overrightarrow{AX}$$

Correct Answer:$$AX:XB \; \text{is} \; 2 : 3$$,$$\frac{2}{5}\overrightarrow{AB}=\overrightarrow{AX}$$

$$\frac{2}{5}\overrightarrow{AB}=\overrightarrow{AX}$$

Q2.
B is a point on the line OL. Match each ratio to the correct vector statement.
Correct Answer:$$OB : BL \; \text{is} \; 1 : 5$$,$$\frac{1}{6}\overrightarrow{OL}=\overrightarrow{OB}$$

$$\frac{1}{6}\overrightarrow{OL}=\overrightarrow{OB}$$

Correct Answer:$$OB : BL \; \text{is} \; 1 : 1$$,$$\frac{1}{2}\overrightarrow{OL}=\overrightarrow{OB}$$

$$\frac{1}{2}\overrightarrow{OL}=\overrightarrow{OB}$$

Correct Answer:$$OB : BL \; \text{is} \; 11 : 1$$,$$\frac{11}{12}\overrightarrow{OL}=\overrightarrow{OB}$$

$$\frac{11}{12}\overrightarrow{OL}=\overrightarrow{OB}$$

Correct Answer:$$OB : BL \; \text{is} \; 1 : 11$$,$$\frac{1}{12}\overrightarrow{OL}=\overrightarrow{OB}$$

$$\frac{1}{12}\overrightarrow{OL}=\overrightarrow{OB}$$

Q3.
O, A and B are in a straight line. You are given that $$\overrightarrow{OA}=12\mathbf{a}+20\mathbf{b}$$ and OA : AB is in the ratio 2 : 3. Work out vector $$\overrightarrow{AB}$$.
$$6\mathbf{a}+10\mathbf{b}$$
$$24\mathbf{a}+40\mathbf{b}$$
Correct answer: $$18\mathbf{a}+30\mathbf{b}$$
$$ 7.2\mathbf{a}+12\mathbf{b}$$
$$8\mathbf{a}+13\mathbf{b}$$
Q4.
You are given that O, A and B are in a straight line, $$\overrightarrow{OA}=12\mathbf{a}+20\mathbf{b}$$ and OB : BA is in the ratio 2 : 3. Work out vector $$\overrightarrow{BA}$$.
$$6\mathbf{a}+10\mathbf{b}$$
$$24\mathbf{a}+40\mathbf{b}$$
$$18\mathbf{a}+30\mathbf{b}$$
Correct answer: $$ 7.2\mathbf{a}+12\mathbf{b}$$
$$8\mathbf{a}+13\mathbf{b}$$
Q5.
XYZ is a triangle. $$\overrightarrow{XY}= 5\mathbf{a}-7.5\mathbf{b}$$ and N lies on $$\overrightarrow{XY}$$ such that $$\overrightarrow{XN}=3\mathbf{a}-4.5\mathbf{b}$$. Write the ratio of XN : NY.
1 : 2
2 : 3
Correct answer: 3 : 2
1 : 3
Q6.
In triangle OAB, $$\overrightarrow{OA}=18\mathbf{a}$$, $$\overrightarrow{OB}=12\mathbf{b}$$. P is on AB. AP:PB = 1:2. $$\overrightarrow{OP}=k(6\mathbf{a}+2\mathbf{b})$$. The value of $$k$$ is .
Correct Answer: 2, k=2, k = 2