IB Maths AI HL Topic 3: Geometry and trigonometry questions

Exam-style questions in the shape of Paper 1 and Paper 2, with full markschemes. Read the markscheme, or type, photograph or draw your answer and get it marked.

Question 1

Paper 2Medium8 marks

A mapping team marks two transmitters, AA and BB and a straight service path CDCD on a coordinate map. The coordinates are measured in kilometres. A receiver must be placed on CDCD so that it is the same distance from both transmitters.

Figure 1 shows the positions of AA BB CC and DD

-4-3-2-11234567-3-2-101234567x-coordinate (km)y-coordinate (km)service path CDABCD
(a)

Find the coordinates of the midpoint MM of ABAB

[1]
(b)

Find the equation of the perpendicular bisector of ABAB Give your answer in the form y=mx+cy=mx+c

[4]
(c)

Hence, determine the coordinates of the receiver.

[3]

Question 2

Paper 2Medium7 marks

A triangular inspection plate is fitted in a three-dimensional frame. From vertex OO the edges OAOA and OBOB are represented by the vectors

a=(2,1,2) m,b=(1,3,−1) m.\mathbf a=(2,1,2)\text{ m},\qquad \mathbf b=(1,3,-1)\text{ m}.

An engineer uses these edges to assess the size and orientation of the plate.

(a)

Determine the area of triangle OABOAB

[2]
(b)

Determine the acute angle between the lines OAOA and OBOB to the nearest 0.1∘0.1^\circ

[2]
(c)

Find the scalar component of a\mathbf a in the direction of b\mathbf b and the magnitude of the component of a\mathbf a perpendicular to b\mathbf b Give each answer to 3 significant figures.

[2]
(d)

Use your answers to part (c) to state whether OAOA is more nearly parallel or perpendicular to OBOB giving a reason.

[1]

Question 3

Paper 2Medium6 marks

For the first 10 hours of a survey, two vessels move in a horizontal plane at constant velocity. Their position vectors, relative to a fixed origin, are

rA(t)=(1.5, 2.0)+t(0.40, 0.30),rB(t)=(6.7, 5.1)+t(−0.35, −0.10),\mathbf r_A(t)=(1.5,\,2.0)+t(0.40,\,0.30),\qquad \mathbf r_B(t)=(6.7,\,5.1)+t(-0.35,\,-0.10),

where coordinates are in kilometres and tt is the time in hours after 08:00.

(a)

Write down the initial position vector of B relative to A, AB→(0)\overrightarrow{AB}(0)

[1]
(b)

Show that

AB→(t)=(5.2, 3.1)+t(−0.75, −0.40).\overrightarrow{AB}(t)=(5.2,\,3.1)+t(-0.75,\,-0.40).
[2]
(c)

Hence determine the time, tt and the distance between the vessels when they are closest during the 10-hour survey. Give both answers to 3 significant figures.

[3]

Question 4

Paper 2Medium6 marks

A road-maintenance vehicle starts at depot A, must travel along every road segment at least once, and must return to A. The roads are undirected.

RoadLength (km)RoadLength (km)
AB4AC6
AD8BC2
BD5CD3
CE7DE4
DF6EF2

The following table gives the least distance, in kilometres, between each pair of locations.

ABCDEF
A–4681214
B4–25911
C62–379
D853–46
E12974–2
F1411962–
(a)

State all the locations of odd degree.

[1]
(b)

Using the least-distance table, determine which pairs of odd-degree locations should have their shortest paths repeated to minimize the additional distance.

[1]
(c)

Hence determine the minimum distance travelled. Explain why the Chinese postman algorithm is appropriate rather than the travelling salesman algorithm, and why the repetitions in part (b) allow the vehicle to return to A after traversing every road.

[4]

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