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=4−x+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.
Determine the coordinates of the point on RR where the bus stop should be located.
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)(y−22)=−3(x−8) (M1)
perpendicular bisector: y=-3x+46y=−3x+46 A1
[5 marks]
attempt to solve simultaneous equations (M1)
x+4=-3x+46x+4=−3x+46
(10.5, 14.5)(10.5, 14.5) A1
[2 marks]