It is asking you to calculate the size of angle a.
Let's practise
Jade draws a diagram of a square meeting a line.
Calculate the size of angle a.
a =°
- 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 angle a?
Look at the diagram carefully and write in any angles that you do know.
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Angle a is smaller than 90°.
You know that the shape is a square and each angle of a square is 90° because each angle is a right angle.
- What else do you notice in the diagram? Where do the angles meet?
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The angles meet at a point on a straight line.
- What do you know about angles that meet at a point on a straight line?
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The angles add to 180°, so:
a + 90° + 26° = 180°
- What can you now say about angle a?
Think about the calculations that you can use to help you.
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a = 180° – 90° – 26°
OR
a = 180° – 116°
- What is your answer?
Check your working.
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Angle a = 64°
64° + 26° = 90°, and two right angles equal 180°.
Your estimate was also smaller than 90°.