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Date May 2021 Marks available 5 Reference code 21M.1.SL.TZ2.6
Level Standard Level Paper Paper 1 Time zone Time zone 2
Command term Find Question number 6 Adapted from N/A

Question

Two schools are represented by points A(2, 20)A(2, 20) and B(14, 24)B(14, 24) on the graph below. A road, represented by the line RR with equation x+y=4x+y=4, passes near the schools. An architect is asked to determine the location of a new bus stop on the road such that it is the same distance from the two schools.

Find the equation of the perpendicular bisector of [AB][AB] . Give your equation in the form y=mx+cy=mx+c.

[5]
a.

Determine the coordinates of the point on RR where the bus stop should be located.

[2]
b.

Markscheme

gradient AB=412  (13)AB=412  (13)             (A1) 

midpoint AB: (8, 22)AB: (8, 22)             (A1) 

gradient of bisector =-1gradient AB=-3=1gradient AB=3             (M1) 

perpendicular bisector: 22=-3×8+b22=3×8+b  OR  (y-22)=-3(x-8)(y22)=3(x8)             (M1) 

perpendicular bisector: y=-3x+46y=3x+46            A1 


[5 marks]

a.

attempt to solve simultaneous equations         (M1) 

x+4=-3x+46x+4=3x+46

(10.5, 14.5)(10.5, 14.5)           A1 


[2 marks]

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Topic 3—Geometry and trigonometry » SL 3.5—Intersection of lines, equations of perpendicular bisectors
Topic 3—Geometry and trigonometry

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