Unit 3: Geometry and Trigonometry

Topic 3.15: Classifying lines (HL only) Questions

Practice 20 exam-style questions for IB Math AA SL Topic 3.15. Review the question stems below, then unlock the full Question Bank to access markschemes, model answers, and AI grading.

11 mark
2026
The denominator of cos θ = |d₁·d₂| / (?) is:
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21 mark
2026
After equating components you get three equations in s and t. To find the intersection you should:
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31 mark
2026
Non-parallel lines whose equations have no common solution are:
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41 mark
2026
Two lines have directions (1, 2, 3) and (2, 4, 6). They are:
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51 mark
2026
If d₁·d₂ = 0, the two lines are:
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61 mark
2026
Directions (1, 1, 0) and (1, 0, 0) make an angle of:
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7Find3 marks
2026
Lines L₁ = (0, 0, 1) + s(1, 1, 2) and L₂ = (0, 2, 1) + t(1, 0, 2). Show that they intersect and find the point of intersection.
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81 mark
2026
Lines r = (1,0,0) + s(1,0,0) and r = (0,0,1) + t(0,1,0) are:
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9Determine2 marks
2026
Determine whether the lines L₁ = (2, 1, 0) + s(1, 2, −1) and L₂ = (3, 1, 4) + t(2, 4, −2) are parallel.
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10Show2 marks
2026
Show that the lines with direction vectors (4, 1, −2) and (1, 2, 3) are perpendicular.
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11Find3 marks
2026
Lines L₁ = (2, 1, 0) + s(1, 0, 1) and L₂ = (0, 3, 5) + t(1, 1, 0). Find the acute angle between L₁ and L₂.
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12Find3 marks
2026
Find the value of k for which the lines with directions (2, k, −1) and (3, 1, 1) are perpendicular.
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13Find3 marks
2026
Two paths are modelled by lines with directions (3, 4, 0) and (0, 4, 3). Find the acute angle between the paths, to the nearest degree.
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14Find3 marks
2026
Lines L₁ = (1, 1, 1) + s(2, −2, 1) and L₂ = (0, 5, 2) + t(2, 1, −2). Find the angle between L₁ and L₂, to the nearest degree.
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15Show that3 marks
2026
Show that the angle between the lines is .
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16Show that4 marks
2026
Show that the lines are parallel and distinct.
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171 mark
2026
Which is true of skew lines but NOT of parallel lines?
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181 mark
2026
Doubling a line's direction vector changes the angle between the lines by:
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191 mark
2026
Why use |d₁·d₂| (with bars) rather than d₁·d₂?
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20Find3 marks
2026
Find the acute angle between the lines with direction vectors d₁ = (1, 2, 2) and d₂ = (2, 3, 6).
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