OAB is a triangle - Edexcel - GCSE Maths - Question 22 - 2018 - Paper 1

Question 22

OAB is a triangle.
OPM and APN are straight lines.
M is the midpoint of AB.
$$
\vec{OA} = a \
\vec{OB} = b
$$
Work out the ratio ON : NB.
Worked Solution & Example Answer:OAB is a triangle - Edexcel - GCSE Maths - Question 22 - 2018 - Paper 1
Process to find \( \vec{OM} \)

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Since M is the midpoint of AB, we can express ( \vec{OM} ) as:
OM=21(OA+OB)=21(a+b)Process to find \( \vec{AP} \)

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Using the coordinates of point P on line ON, we can write:
OP=x⋅OA+y⋅OB
where ( x + y = 1 ) and for ( OP:PM = 3:2 ), we find that ( x = 0.6 ) and ( y = 0.4 ). Therefore, we can conclude that:
OP=0.6a+0.4bProcess to find \( \vec{ON} \)

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Let ( \vec{ON} = k \cdot \vec{OP} ). Thus,
ON=k(0.6a+0.4b)
From the ratio we set up using segments, we can say that:
( ON:NB = 3:2 ). Therefore, using the comparison based on the sections derived, we reach:
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