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Geometry: Collinear Points
If points S(w, 3), T(1, –7) and U( –2, –17) are collinear,
the value of w must be

tickcross



Worked Solution

If the three points S, T, U are on the same straight line then the slope (gradient) of TU equals the slope of the line US
The slope of TU =
–17 – (–7)
---
–2 – 1
 =
–10
---
–3
 =
10
---
3
The slope of US =
3 – (–17)
---
w – (–2)
 =
20
---
w + 2
Because these two slopes are equal then w must be 4

© MEI Produced by Dr Ron Knott, revised 20 July 2004
tom . button [AT] mei . org . uk 		Test reference: GeomCollinear.html?ref=61319