Use angle relationships
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Log in to continueExplain unknown angles using straight lines, points and crossing lines.
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Two adjacent angles make a straight angle. One is 22°. What is the other?
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Answer: 158 degrees
- A straight angle measures 180°.
- 180 − 22 = 158°.
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Curriculum reference
Victorian Curriculum F–10 Version 2.0
Pi Leo practice scope
Explain unknown angles using straight lines, points and crossing lines.
Read the official VCAA curriculum description (VC2M6M04)
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Activities to practise beyond the quiz
- Supported by the guided activity; selecting an MCQ does not demonstrate this action.
- VC2M6M04-C01Adjacent angles forming a straight line sum to 180°. This total, rather than appearance, determines the missing angle.
- VC2M6M04-C02Non-overlapping angles around a point sum to 360°. Add the known angles before subtracting.
- VC2M6M04-C03When two straight lines cross, opposite angles are equal. Adjacent angles are supplementary, which also explains the opposite-angle equality.
- VC2M6M04-C04Communicating a geometric chain of reasoning and checking it with tools.
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Subskills
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Descriptor-derived subskills
- D01Complete a straight angleAdjacent angles forming a straight line sum to 180°. This total, rather than appearance, determines the missing angle.
- D02Complete a full turnNon-overlapping angles around a point sum to 360°. Add the known angles before subtracting.
- D03Use vertically opposite equalityWhen two straight lines cross, opposite angles are equal. Adjacent angles are supplementary, which also explains the opposite-angle equality.