4MA0 Foundation June 2015 Paper 1R Q9
9 \(CDF\) and \(DEF\) are isosceles triangles.
\(CD = DF = EF\).
\(ACDE\) and \(BCF\) are straight lines.

Diagram NOT accurately drawn
(a)
(i) Find the value of \(x\).
(ii) Give a reason for your answer.
(2)(b) Calculate the value of \(y\). (3)
| Scheme | Marks |
|---|---|
| (i) Answer: 35 | B1 |
| (ii) Answer: Vertically opposite angles are equal | B1 |
| (2) |
Notes
B1: accept “Vertically opposite” or “opposite angles”
| Scheme | Marks |
|---|---|
| \(CDF = 180 - 2 \times 35\) (= 110) or \(FDE = 35 + 35\) (= 70) or \(FDE = 180 - 110\) (= 70) or \(DEF = 70\) | M1 |
| (\(y\) =) 180 – 2 × 70 | M1 |
| 40 | A1 |
| (3) | |
| Total 5 marks |
Notes
M1: could be marked on diagram
M1: a complete correct method