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Date May 2022 Marks available 2 Reference code 22M.1.SL.TZ1.1
Level Standard Level Paper Paper 1 (without calculator) Time zone Time zone 1
Command term Find Question number 1 Adapted from N/A

Question

Consider the points A(-2, 20)A(2, 20), B(4, 6)B(4, 6) and C(-14, 12)C(14, 12). The line LL passes through the point AA and is perpendicular to [BC][BC].

Find the equation of LL.

[3]
a.

The line LL passes through the point (k, 2)(k, 2).

Find the value of kk.

[2]
b.

Markscheme

mBC=12-6-14-4 (=-13)mBC=126144 (=13)        (A1)

finding mL=-1mBCmL=1mBC using their mBCmBC        (M1)

mL=3mL=3

y-20=3(x+2),  y=3x+26y20=3(x+2),  y=3x+26        A1

 

Note: Do not accept L=3x+26L=3x+26

 

[3 marks]

a.

substituting (k, 2)(k, 2) into their LL        (M1)

2-20=3(k+2)220=3(k+2)  OR  2=3k+262=3k+26

k=-8k=8        A1

 

[2 marks]

b.

Examiners report

Finding the gradient of a line was well understood and many candidates also correctly found the perpendicular slope. Even with an error in their part (a), follow through marks in part (b) allowed many candidates to earn full marks for finding k despite their incorrect equation resulting in arithmetic of greater complexity.

a.
[N/A]
b.

Syllabus sections

Topic 2—Functions » SL 2.1—Equations of straight lines, parallel and perpendicular
Topic 2—Functions

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