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.
Hence, find the exact area of the non-shaded region.
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]
EITHER
θ=2π-AˆOB (=2π-1)θ=2π−AˆOB(=2π−1) (M1)
Area of non-shaded region =12(2π-1)(42)=12(2π−1)(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))=16π−8 (=8(2π−1)) A1
[3 marks]