Date | November 2008 | Marks available | 7 | Reference code | 08N.2.hl.TZ0.1 |
Level | HL only | Paper | 2 | Time zone | TZ0 |
Command term | Find | Question number | 1 | Adapted from | N/A |
Question
In a triangle ABC, ˆA=35∘, BC = 4 cm and AC = 6.5 cm. Find the possible values of ˆB and the corresponding values of AB.
Markscheme
sinB6.5=sin35∘4 M1
ˆB=68.8∘ or 111∘ A1A1
ˆC=76.2∘ or 33.8∘ (accept 34∘) A1
ABsinC=BCsinA
ABsin76.2∘=4sin35∘ (M1)
AB = 6.77 cm A1
ABsin33.8∘=4sin35∘
AB = 3.88 cm(accept 3.90) A1
[7 marks]
Examiners report
Most candidates realised that the sine rule was the best option although some used the more difficult cosine rule which was an alternative method. Many candidates failed to realise that there were two solutions even though the question suggested this. Many candidates were given an arithmetic penalty for giving one of the possible of values ˆB as 112.2° instead of 111°.