Higher November 2021 Paper 5 Q11
11 The diagram shows a quadrilateral ABCD.
AD = 10 cm, angle BAD = 30° and angle ABD = angle BDC = 90°.
Not to scale
The ratio of length BD to length DC is 1 : 2.4 .
Work out length BC.
You must show your working. [7]
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| 13 with correct working | 7 | M1 for \(\dfrac{BD}{10} = \sin 30\) oe B1 for sin 30 = 0.5 soi A1 for [BD =] 5 M1 for their BD × 2.4 oe A1 for CD = 12 | “Correct working” requires evidence of at least M1 or B1 and M1M1 or alternate convincing approach Answer 12 gets A0 unless CD = 12 shown in working or on diagram |
| M1 for (their BD)² + (their CD)² [ = BC²] oe If 0 scored SC3 for answer 13 with no working or SC2 for CD = 12 with no working or SC1 for BD = 5 with no working | SCs may be seen on the diagram | ||