Calculating: Error Analysis & Misconceptions
Mathematics
Year 9
10 questions
~20 mins
1 views0 downloads
About This Worksheet
This worksheet focuses on calculating the measures of vertically opposite angles, highlighting common misconceptions and error analysis to deepen understanding.
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Calculating: Error Analysis & Misconceptions
Subject: MathematicsGrade: Year 9
Name:
Date:
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Untitled Worksheet
Grade Year 9
A
Fluency & Practice
Answer all questions. Show your working in the grid spaces provided.
1.
Calculate the measure of angle A if it is vertically opposite to angle B, which measures 65°.
[2 marks]2.
In a pair of vertically opposite angles, one angle is 120°. What is the measure of the other?
[2 marks]3.
True or False: Vertically opposite angles are always supplementary.
[1 mark]ATrue
BFalse
B
Problem Solving & Reasoning
Work through the multi-step problems carefully. Provide explanations where necessary.
1.
Two intersecting lines form two pairs of vertically opposite angles. If one of the angles measures (3x + 20)° and the other measures (2x + 55)°, find the value of x and the angles.
[4 marks]2.
In a diagram, two lines intersect creating vertically opposite angles. If one angle is 45°, what is the size of the adjacent angle that is supplementary to the vertically opposite angle?
[3 marks]C
Real-world Applications
Read the scenario and solve the problem based on calculating angles.
1.
A street intersection has two roads crossing, forming vertically opposite angles. If one of the angles measures 80°, what is the measure of the opposite angle? How might this information be useful for traffic signal placement?
[4 marks]D
Challenge & Extension
Attempt these more difficult problems. Show all your working clearly.
1.
Two intersecting lines form an angle of 110°. Find the measure of the vertically opposite angle, and then calculate the supplementary angles formed with a third line crossing one of the original lines at a right angle.
[4 marks]2.
Construct a diagram where two lines intersect, creating angles of 65° and 115°. Calculate the remaining angles and identify any misconceptions if students assume all vertically opposite angles are equal.
[3 marks]E
Mixed Review & Error Analysis
Identify the common mistake in each problem and correct it. Explain your reasoning.
1.
A student states: 'If two angles are vertically opposite, then their sum is 180°.' Is this correct? If not, identify the mistake and provide the correct understanding.
[3 marks]2.
A diagram shows two intersecting lines with one angle marked 70°. The student calculates the vertically opposite angle as 70°, which is correct. However, they then incorrectly assume the adjacent angle is also 70°. Explain the mistake and state the correct measures.
[3 marks]Quick Actions
What is Remix?
Create a new worksheet based on this one. Change the grade level, topic, number of questions, or difficulty - then generate a fresh version.
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Details
- Created
- 1/1/2026
- Updated
- 1/1/2026
- Type
- worksheet