Foundation November 2018 Paper 2 Q19
19 Here is a right-angled triangle.
Not drawn accurately
Show that \(\quad x = 12\) [2 marks]
| Answer | Mark | Comments |
|---|---|---|
| Alternative method 1 | ||
| \(7.2^2 + 9.6^2\ (= 51.84 + 92.16) = 144\) and \(\sqrt{144} = 12\) or \(12^2 = 144\) | B2 | B1 \(7.2^2\) and \(9.6^2\) oe |
| Alternative method 2 | ||
| \(12^2 - 7.2^2\ (= 144 - 51.84) = 92.16\) and \(\sqrt{92.16} = 9.6\) or \(9.6^2 = 92.16\) | B2 | B1 \(12^2\) and \(7.2^2\) oe |
| Alternative method 3 | ||
| \(12^2 - 9.6^2\ (= 144 - 92.16) = 51.84\) and \(\sqrt{51.84} = 7.2\) or \(7.2^2 = 51.84\) | B2 | B1 \(12^2\) and \(9.6^2\) oe |
| Alternative method 4 | ||
| \(\sqrt{7.2^2 + 9.6^2} = 12\) or \(\sqrt{12^2 - 7.2^2} = 9.6\) or \(\sqrt{12^2 - 9.6^2} = 7.2\) | B2 | condone \(7.2^2 + 9.6^2 = 12^2\) or \(12^2 - 7.2^2 = 9.6^2\) or \(12^2 - 9.6^2 = 7.2^2\) B1 any two of \(7.2^2\), \(9.6^2\) and \(12^2\) oe |
Additional guidance
| \(7.2^2 + 9.6^2 = 144\), \(x^2 = 144\), \(x = 12\) | B2 |
| Do not accept \(144 \div 12 = 12\) for \(\sqrt{144} = 12\) | |
| Do not accept incorrect statements for B2 eg \(7.2^2 + 9.6^2 = \sqrt{144} = 12\) | B1 |
| Do not accept scale drawing | |
| For eg \(12^2\) accept \(12 \times 12\) |