Foundation June 2018 Paper 2 Q15
15 Mary needs to work out the size of angle \(x\) in this diagram.
She writes
\(x = 63^\circ\) because base angles of an isosceles triangle are equal.
Mary is wrong.
(a) Explain why. (1)
William needs to work out the size of angle \(y\) in this diagram.
William writes
| Working | Reason |
|---|---|
| angle \(EGH = 57^\circ\) | because corresponding angles are equal |
| \(y = 180^\circ - 57^\circ\) \(y = 123^\circ\) | because angles on a straight line add up to \(180^\circ\) |
One of William’s reasons is wrong.
(b) Write down the correct reason. (1)
| Answer | Mark | Mark scheme |
|---|---|---|
| Correct evaluation | C1 | for explanation eg \(x\) is not a base angle or states \(x = 54^\circ\) |
| Answer | Mark | Mark scheme |
|---|---|---|
| Correct or corrected reasoning given | C1 | eg (because) alternate angles are equal, or Allied angles / Co-interior angles add up to 180 or they are not corresponding (they are alternate) OR selects correct reason used by William |