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Date May 2017 Marks available 3 Reference code 17M.2.SL.TZ2.T_4
Level Standard Level Paper Paper 2 Time zone Time zone 2
Command term Find Question number T_4 Adapted from N/A

Question

The quadrilateral ABCD represents a park, where AB=120 m, AD=95 m and DC=100 m. Angle DAB is 70° and angle DCB is 110°. This information is shown in the following diagram.

M17/5/MATSD/SP2/ENG/TZ2/04

A straight path through the park joins the points B and D.

A new path, CE, is to be built such that E is the point on BD closest to C.

The section of the park represented by triangle DCE will be used for a charity race. A track will be marked along the sides of this section.

Find the length of the path BD.

[3]
a.

Show that angle DBC is 48.7°, correct to three significant figures.

[3]
b.

Find the area of the park.

[4]
c.

Find the length of the path CE.

[2]
d.

Calculate the total length of the track.

[3]
e.

Markscheme

* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.

(BD2=) 952+12022×95×120×cos70     (M1)(A1)

 

Note:     Award (M1) for substituted cosine rule, (A1) for correct substitution.

 

(BD=) 125 (m) (125.007 (m))     (A1)(G2)

 

[3 marks]

a.

sinDBC100=sin110125.007     (M1)(A1)(ft)

 

Note:     Award (M1) for substituted sine rule, (A1)(ft) for correct substitution.

Follow through from their answer to part (a).

 

(DBC=) 48.7384     (A1)(ft)

(DBC=) 48.7     (AG)

 

Notes:     Award the final (A1)(ft) only if both their unrounded answer and 48.7° is seen. Follow through from their answer to part (a), only if their unrounded answer rounds to 48.7°.

 

[3 marks]

b.

12×125.007×100×sin21.3+12×95×120×sin70     (A1)(M1)(M1)

 

Note:     Award (A1) for 21.3° (21.2615…) seen, (M1) for substitution into (at least) one area of triangle formula in the form 12absinc, (M1) for their correct substitutions and adding the two areas.

 

7630 m2 (7626.70m2)     (A1)(ft)(G3)

 

Notes:     Follow through from their answers to part (a). Accept 7620 m2 (7622.79m2) from use of 48.7384…

 

[4 marks]

c.

(CE=) 100×sin21.3     (M1)

(CE=) 36.3 (m) (36.3251 (m))     (A1)(ft)(G2)

 

Note:     Follow through from their angle 21.3° in part (c). Award (M0)(A0) for halving 110° and/or assuming E is the midpoint of BD in any method seen.

 

OR

area of BCD=12BD×CE     (M1)

(CE=) 36.3 (m) (36.3251 (m))     (A1)(ft)(G2)

 

Note:     Follow through from parts (a) and (c). Award (M0)(A0) for halving 110° and/or assuming E is the midpoint of BD in any method seen.

 

[2 marks]

d.

100236.32512+100+36.3251     (M1)(M1)

 

Note:     Award (M1) for correct use of Pythagoras to find DE (or correct trigonometric equation, 100×cos21.3, to find DE), (M1) for the sum of 100, their DE and their CE.

 

229 (m) (229.494 (m))     (A1)(ft)(G2)

 

Note:     Follow through from part (d). Use of 3 sf values gives an answer of 230 (m) (229.5 (m)).

 

[3 marks]

e.

Examiners report

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Syllabus sections

Topic 3— Geometry and trigonometry » SL 3.2—2d and 3d trig, sine rule, cosine rule, area
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Topic 3— Geometry and trigonometry

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