Intermediate June 2017 Unit 2 Q15
15. Construct an accurate drawing of triangle ABC, where AB = 7 cm, \(A\widehat{B}C\) = 90° and \(B\widehat{A}C\) = 60°.
Use only a ruler and a pair of compasses.
The side AB has been drawn for you.
You must show your construction arcs. [3]
On screen this diagram may not be shown at actual size. To measure it, use the question paper (PDF) printed at 100%.
| Scheme | Marks | Comments |
|---|---|---|
| Correct construction of 90° at point B. | B2 | With sight of accurate ‘method arcs’. e.g . (i) AB extended with arcs either side of B on extended line AB (or line AB extended by 7cm) AND arcs above or below point B). (ii) construction of 60°, 120° and a bisection. B1 for complete method but line not drawn. |
| Correct construction of angle BAC = 60°. | B1 | With sight of accurate ‘method arcs’ and line drawn. If all three marks gained but triangle not completed penalise −1 mark. (Treat reversal of angles as a misread.) |