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Date May 2021 Marks available 3 Reference code 21M.1.SL.TZ2.1
Level Standard Level Paper Paper 1 (without calculator) Time zone Time zone 2
Command term Hence and Find Question number 1 Adapted from N/A

Question

The following diagram shows a circle with centre OO and radius rr.

Points AA and BB lie on the circumference of the circle, and AˆOB=1 radianAˆOB=1 radian.

The perimeter of the shaded region is 1212.

Find the value of rr.

[3]
a.

Hence, find the exact area of the non-shaded region.

[3]
b.

Markscheme

minor arc ABAB has length rr                  (A1)

recognition that perimeter of shaded sector is 3r3r                     (A1)

3r=123r=12

r=4r=4               A1

 

[3 marks]

a.

EITHER
θ=2π-AˆOB(=2π-1)θ=2πAˆOB(=2π1)             (M1)

Area of non-shaded region =12(2π-1)(42)=12(2π1)(42)            (A1)

 

OR

area of circle - area of shaded sector              (M1)

16π-(12×1×42)16π(12×1×42)              (A1)

 

THEN

area =16π-8 (=8(2π-1))=16π8 (=8(2π1))          A1

 

[3 marks]

b.

Examiners report

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

Syllabus sections

Topic 3— Geometry and trigonometry » SL 3.4—Circle: radians, arcs, sectors
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Topic 3— Geometry and trigonometry

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