Date | May 2008 | Marks available | 3 | Reference code | 08M.1.sl.TZ1.7 |
Level | SL only | Paper | 1 | Time zone | TZ1 |
Command term | Find | Question number | 7 | Adapted from | N/A |
Question
Triangle ABC is such that AC is 7 cm, angle ABC is 65∘ and angle ACB is 30∘.
Sketch the triangle writing in the side length and angles.
Calculate the length of AB.
Find the area of triangle ABC.
Markscheme
(A1) (C1)
Note: (A1) for fully labelled sketch.
[1 mark]
Unit penalty (UP) may apply in this question.
ABsin30=7sin65 (M1)
(UP) AB=3.86 cm (A1)(ft) (C2)
Note: (M1) for use of sine rule with correct values substituted.
[2 marks]
Unit penalty (UP) may apply in this question.
Angle BAC=85∘ (A1)
Area=12×7×3.86×sin85∘ (M1)
(UP) =13.5 cm2 (A1)(ft) (C3)
[3 marks]
Examiners report
The triangle was drawn correctly by most and a majority correctly found the length of AB - a few did not write down the units (cm) and so lost a Unit penalty mark. There was still a significant number who tried to use right-angled trigonometry to find the length.
Finding the area of the triangle was mixed with many again assuming the existence of a right angle. Some candidates had their calculators in radian mode rather than degree mode.
The triangle was drawn correctly by most and a majority correctly found the length of AB - a few did not write down the units (cm) and so lost a Unit penalty mark. There was still a significant number who tried to use right-angled trigonometry to find the length.
Finding the area of the triangle was mixed with many again assuming the existence of a right angle. Some candidates had their calculators in radian mode rather than degree mode.
The triangle was drawn correctly by most and a majority correctly found the length of AB - a few did not write down the units (cm) and so lost a Unit penalty mark. There was still a significant number who tried to use right-angled trigonometry to find the length.
Finding the area of the triangle was mixed with many again assuming the existence of a right angle. Some candidates had their calculators in radian mode rather than degree mode.