ABCD is a trapezium with AB parallel to DC. DC = 15 cm and AB = x cm. The perpendicular distance between AB and DC is 3 cm less than the length of AB. The area of ABCD is 75 cm². Show that x² + 12x – 195 = 0.
- (a)(i)ABCD is a trapezium with AB parallel to DC. DC = 15 cm and AB = x cm. The perpendicular distance between AB and DC is 3 cm less than the length of AB. The area of ABCD is 75 cm². Show that x² + 12x – 195 = 0.[2]
- (a)(ii)Find AB, giving your answer correct to 1 decimal place.[3]
- (a)(iii)AD is 0.8 cm longer than BC. Given that the perimeter of the trapezium is 38.0 cm, calculate AD.[2]
- (b)(i)Another trapezium, LMNO, has LM parallel to ON. The reflex angle LMN = 252°. Calculate ∠MNO.[2]
- (b)(ii)The ratios of the angles inside the trapezium are LÔN : LMN=1:2 and OLM : MÑO=1:k. Find k, giving your answer as a fraction in its simplest form.[3]
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Mark scheme
Marking points from the official mark scheme (Oct/Nov 2015). The mark or mark type is shown in brackets.
- [2] Correct expansion leading to x² + 12x – 195 = 0 www
- M1 Or equivalent equation for area
- [3] 9.2 cao
- B2 for 9.19[8...] or 9.2[0] seen
- OR B1 for √12² - 4 × 1 × -195 soi
- And B1 for (-12 ± √their 924) / 2 oe
- [2] 7.3
- M1 for 2AD - 0.8 + 15 + their 9.2 = 38.0 oe
- Or 2BC + 0.8 + 15 + their 9.2 = 38.0 oe
- Or SC1 for answer [BC = ] 6.5
- [2] 72°
- B1 for LMN = 108° seen
- [3] 4/7
- M1 for 126 : their 72 soi or B1 for 126 seen
- Or SC2 for answer 7/4
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