78 3 H Using angles on a straight line. = 180° 58° = 122° – Angle ADB = = 180° (32° + 122°) – = 180° 154° = 26° – Use the sine rule. = sin 32° × e = sin 32° × 63.872 816 9 e = 63.847 436 Using trigonometry: M1 M1 for method for finding angle ABD sin 58° = B1 B1 for 26° sin 58° c = e = 28.704 253 7 M1 M1 for use of sine rule So the height of the tower is 29 m to the nearest metre. B1 B1 for and any rounding e M1 M1 for correct use of trigonometry M1 M1 for correct expression for c A1 A1 for 29 answer rounded to 2 or 3 sf C1 A1 for complete accurate solution well laid out. 8
78 Using angles on a straight line. = 180° – 58° = 122° Angle ADB = = 180° – (32° + 122°) = 180° – 154° = 26° Use the sine rule. e = sin 32° × e = sin 32° × 63.872 816 9 = 63.847 436 Using trigonometry: sin 58° = c = e sin 58° = 28.704 253 7 So the height of the tower is 29 m to the nearest metre. M1 B1 M1 B1 M1 M1 A1 C1 3 M1 for method for finding angle ABD B1 for 26° M1 for use of sine rule B1 for e and any rounding M1 for correct use of trigonometry M1 for correct expression for c A1 for 29 answer rounded to 2 or 3 sf A1 for complete accurate solution well laid out. H 8
Higher_Skills_Geometry_MarkScheme_Edexcel.docx