It is asking you to work out the size of angle x in the triangle.
Let's practise
What is the size of angle x?
x =°
- Read the question and then read it again. What is it asking you to do?
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- What angle sizes do you already know?
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One angle is 105° and another is 45°.
- What do you know about the sum of angles in a triangle?
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Angles in a triangle add up to 180°.
- To calculate the size of the missing angle, subtract the size of the angles you do know from 180°, or think about what you need to add to get to 180°.
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180° – 105° – 45° = 30°
OR
105° + 45° = 150°
180° – 150° = 30°
- What is your answer?
Check your working.
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30°
You can use the inverse to check that 105° + 45° + 30° = 180°.