It is asking you to calculate the sizes of angles x and y.
Let's practise
The diagram shows an equilateral triangle and a straight line.
Calculate the size of angles x and y.
x =°
y =°
- Read the question and then read it again. What is it asking you to do?
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- Can you estimate the size of angles x and y?
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Angle x is greater than 90° and angle y is smaller than 90°.
Angles x and y meet at a point on a straight line, so they must sum to 180°.
- Look at the diagram carefully and write in any angles that you do know.
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The angle 140° is on a straight line so you can write in 40°.
- What shape is used in the diagram?
How could that help you?
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An equilateral triangle. Each angle in an equilateral triangle is 60°.
- Write in any more angles that you now know.
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You can use this to find the angles in the other triangle made by the straight line.
180 – 20 – 60 = 100
- What can you now say about angles x and y?
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180 – 20 – 60 = 100
Angle x must equal 100° as it is vertically opposite.
Angle y must equal 80° as it meets 100° at a point on a straight line.
- What is your answer?
Check your working.
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x = 100°
y = 80°
Your estimate was that angle x is greater than 90° and angle y is smaller than 90°, and both angles sum to 180°.