Foundation June 2018 Paper 2 Q20
20
(a) Here are three similar triangles.
Not to scale
Work out the value of \(x\). [3]
(b) The diagram shows two right-angled triangles, OAB and OCD.
Work out the length of BD. [3]
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| 3.5 oe | 3 | M1 for 21 ÷ (15 ÷ 5) soi and M1 for their 7 ÷ (8 ÷ 4) oe Or M1 for 8 \(\times\) (15 ÷ 5) soi and M1 for 21 ÷ (their ‘24’ ÷ 4) oe Or M1 4 x (5 ÷ 8) soi and M1 for their 2.5 x (21 ÷ 15) Or B1 scale factor from small triangle to the large triangle is 6 soi | Accept 7 correctly placed on the diagram Accept 24 correctly placed on the diagram Accept 2.5 correctly placed on the diagram Eg may be x2 then x3 correctly shown on diagram |
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| 10.5 or \(10\frac{1}{2}\) or \(\dfrac{21}{2}\) | 3 | M1 for \(\dfrac{\text{OD}}{14} = \dfrac{7}{4}\) oe or 7 : 4 = OD : 14 A1 for OD = \(\dfrac{49}{2}\) oe | Eg 14 x 1.75 |