(a) Is it possible for an isosceles triangle to have an angle of 140°? Circle your answer. You must give an explanation for your answer. [1]
YES NO
(b) Is it possible for a rhombus to have an angle of 120° and an angle of 30°? Circle your answer. You must give an explanation for your answer. [1]
YES NO
(c)
Diagram not drawn to scale
Which of the following equations is correct for the diagram shown above? Circle your answer. [1]
\(a + b = 30\) \(a + b = 210\) \(b - a = 150\)
\(a - b = 150\) \(a + b = 150\)
Mark scheme (a)
Scheme
Marks
Comments
YES AND a valid explanation. e.g. ‘ the other two angles would be (both) 20(°)’ e.g. diagram showing (isosceles) triangle with angles of 140°, 20° and 20°.
E1
A valid explanation implies YES circled if not otherwise contradicted (by circling NO).
Explanations must engage with the specific triangle given (with an angle of 140°) and not isosceles triangles in general.
Mark scheme (b)
Scheme
Marks
Comments
NO AND a valid explanation. e.g. ‘120(°) + 30(°) ≠ 180(°)’ ‘the two angles add to 150(°), not 180(°) ‘120(°) + 30(°) + 120(°) + 30(°) ≠ 360(°)’ ‘the four angles add to 300(°), not 360(°)
E1
Allow ‘the two angles must equal 180°’. Do not accept ‘the four angles must equal 360°’ unless it is made clear that the rhombus has two pairs of equal angles. A valid explanation implies NO circled if not otherwise contradicted (by circling YES).
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