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Date None Specimen Marks available 5 Reference code SPNone.2.hl.TZ0.7
Level HL only Paper 2 Time zone TZ0
Command term Determine Question number 7 Adapted from N/A

Question

A ship, S, is 10 km north of a motorboat, M, at 12.00pm. The ship is travelling northeast with a constant velocity of 20 kmhr1. The motorboat wishes to intercept the ship and it moves with a constant velocity of 30 kmhr1 in a direction θ degrees east of north. In order for the interception to take place, determine

the value of θ.

[4]
a.

the time at which the interception occurs, correct to the nearest minute.

[5]
b.

Markscheme

let the interception occur at the point P, t hrs after 12:00

then, SP = 20t and MP = 30t     A1

using the sine rule,

SPMP=23=sinθsin135     M1A1

whence θ=28.1     A1

[4 marks]

a.

using the sine rule again,

MPMS=sin135sin(4528.1255)     M1A1

30t=10×sin135sin16.8745     M1

t=0.81199     A1

the interception occurs at 12:49     A1

[5 marks]

b.

Examiners report

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

Syllabus sections

Topic 3 - Core: Circular functions and trigonometry » 3.7 » The sine rule including the ambiguous case.

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