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 1Medium6 marks

A mapping team approximates a wetland by triangle ABCABC The horizontal distance between survey stations AA and BB is 1.80 km1.80\text{ km} The measured interior angles are ∠BAC=52.6∘\angle BAC=52.6^\circ and ∠ABC=68.3∘\angle ABC=68.3^\circ

The wetland qualifies for a reserve if its mapped area is at least 1.20 km21.20\text{ km}^2

(a)

Find ∠ACB\angle ACB

[1]
(b)

Show that AC=1.95 kmAC=1.95\text{ km} correct to three significant figures.

[2]
(c)

Hence, using your answer to part (b), calculate the area of triangle ABCABC correct to three significant figures, and state whether the wetland qualifies for a reserve.

[3]

Question 2

Paper 1Medium6 marks

A surveyor uses triangulation to estimate the area of a triangular wetland ABCABC Points AA and BB lie on an accessible straight bank, and AB=dAB=d metres. The measured interior angles are ∠BAC=48∘\angle BAC=48^\circ and ∠ABC=67∘\angle ABC=67^\circ

(a)

Find ∠ACB\angle ACB

[1]
(b)

Show that the area TT in m2\text{m}^2 is approximately given by T=0.377d2T=0.377d^2

[2]
(c)

The surveyor wants to map a region with an area of at least 6000 m26000\text{ m}^2 Determine the required value of dd to 3 significant figures. Hence state whether a baseline of 125 m125\text{ m} is sufficient.

[3]

Question 3

Paper 1Hard6 marks

A flat map uses Cartesian coordinates to locate radio beacons. The segment ABAB lies on the line 3x−4y−10=03x-4y-10=0 and its midpoint is M(2,−1)M(2,-1)

(a)

Determine the equation of the perpendicular bisector of ABAB giving your answer in the form ax+by+c=0ax+by+c=0

[2]
(b)

Beacons CC and DD have coordinates C(−2,4)C(-2,4) and D(4,2)D(4,2) An emergency receiver QQ must be equidistant from AA and BB and also equidistant from CC and DD

Using your answer to (a), determine the exact coordinates of QQ

[4]

Question 4

Paper 1Medium6 marks

Two survey boats, A and B, move at constant velocities in a horizontal plane. Coordinates are measured in metres, with the xx-axis pointing east and the yy-axis pointing north. At t=0t=0 their position vectors are

rA=(120,30),rB=(20,100),\mathbf r_A=(120,30), \qquad \mathbf r_B=(20,100),

and their velocity vectors are

vA=(3,1),vB=(5,−2),\mathbf v_A=(3,1), \qquad \mathbf v_B=(5,-2),

in m s−1\text{m s}^{-1} The time tt is measured in seconds.

(a)

Find an expression, in terms of tt for the relative position vector of B from A, AB→\overrightarrow{AB}

[2]
(b)

Using your answer to part (a), determine the time t≥0t\geq 0 at which the boats are closest and their minimum separation. Give both answers to 3 significant figures.

[4]

Question 5

Paper 1Medium8 marks

A courier moves between three depots, AA BB and CC The directed routes leaving each depot are shown below.

DepotDepots reachable in one leg
AAB,CB, C
BBA,CA, C
CCAA

At each depot, the courier chooses uniformly from the routes leaving that depot. Use the convention that the entry in row ii column jj of a transition matrix is the probability of moving from depot ii to depot jj

(a)

Write down the adjacency matrix AA for this network, using the order A,B,CA,B,C for both rows and columns.

[2]
(b)

Find the number of two-leg walks from AA back to AA using the appropriate entry of A2A^2

[2]
(c)

Construct the transition matrix TT for the courier’s movements, using the order A,B,CA,B,C for both rows and columns.

[2]
(d)

Using your transition matrix, find the probability that the courier is at AA after exactly two legs, starting from AA

[2]

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