Date | November 2021 | Marks available | 2 | Reference code | 21N.1.SL.TZ0.4 |
Level | Standard Level | Paper | Paper 1 | Time zone | Time zone 0 |
Command term | Find | Question number | 4 | Adapted from | N/A |
Question
Dilara is designing a kite ABCDABCD on a set of coordinate axes in which one unit represents 10 cm10cm.
The coordinates of AA, BB and CC are (2, 0), (0, 4)(2, 0), (0, 4) and (4, 6)(4, 6) respectively. Point DD lies on the xx-axis. [AC][AC] is perpendicular to [BD][BD]. This information is shown in the following diagram.
Find the gradient of the line through AA and CC.
Write down the gradient of the line through BB and DD.
Find the equation of the line through BB and DD. Give your answer in the form ax+by+d=0ax+by+d=0, where a, ba, b and dd are integers.
Write down the xx-coordinate of point DD.
Markscheme
m=6-04-2=3m=6−04−2=3 (M1)A1
[2 marks]
(m=) -13 (-0.333, -0.333333…)(m=) −13 (−0.333, −0.333333…) A1
[1 mark]
an equation of line with a correct intercept and either of their gradients from (a) or (b) (M1)
e.g. y=-13x+4y=−13x+4 OR y-4=-13(x-0)y−4=−13(x−0)
Note: Award (M1) for substituting either of their gradients from parts (a) or (b) and point BB or (3, 3)(3, 3) into equation of a line.
x+3y-12=0x+3y−12=0 or any integer multiple A1
[2 marks]
(x=) 12(x=) 12 A1
[1 mark]
Examiners report
This question was overall well done by most candidates. In part (a) calculating the gradient was correctly done with few errors noted where candidates swapped the yy and xx coordinates in the gradient formula. Some candidates left their answer as 6363 which resulted in a loss of the final mark. There was some confusion with the gradient of a line and the gradient of the perpendicular line in part (a). Some candidates found the perpendicular gradient in part (a). Although many candidates were able to write an appropriate equation of the line through BDBD, several did not express their answer in the required form ax+by+d=0ax+by+d=0, where aa, bb and dd are integers. Many final answers were given as y=13x+4y=13x+4 or y-13x-4=0y−13x−4=0. In part (d), writing the xx-coordinate of point DD was well done by most candidates. Some candidates wrote a coordinate pair rather than just the xx-coordinate as required.
This question was overall well done by most candidates. In part (a) calculating the gradient was correctly done with few errors noted where candidates swapped the yy and xx coordinates in the gradient formula. Some candidates left their answer as 6363 which resulted in a loss of the final mark. There was some confusion with the gradient of a line and the gradient of the perpendicular line in part (a). Some candidates found the perpendicular gradient in part (a). Although many candidates were able to write an appropriate equation of the line through BDBD, several did not express their answer in the required form ax+by+d=0ax+by+d=0, where aa, bb and dd are integers. Many final answers were given as y=13x+4y=13x+4 or y-13x-4=0y−13x−4=0. In part (d), writing the xx-coordinate of point DD was well done by most candidates. Some candidates wrote a coordinate pair rather than just the xx-coordinate as required.
This question was overall well done by most candidates. In part (a) calculating the gradient was correctly done with few errors noted where candidates swapped the yy and xx coordinates in the gradient formula. Some candidates left their answer as 6363 which resulted in a loss of the final mark. There was some confusion with the gradient of a line and the gradient of the perpendicular line in part (a). Some candidates found the perpendicular gradient in part (a). Although many candidates were able to write an appropriate equation of the line through BDBD, several did not express their answer in the required form ax+by+d=0ax+by+d=0, where aa, bb and dd are integers. Many final answers were given as y=13x+4y=13x+4 or y-13x-4=0y−13x−4=0. In part (d), writing the xx-coordinate of point DD was well done by most candidates. Some candidates wrote a coordinate pair rather than just the xx-coordinate as required.
This question was overall well done by most candidates. In part (a) calculating the gradient was correctly done with few errors noted where candidates swapped the yy and xx coordinates in the gradient formula. Some candidates left their answer as 6363 which resulted in a loss of the final mark. There was some confusion with the gradient of a line and the gradient of the perpendicular line in part (a). Some candidates found the perpendicular gradient in part (a). Although many candidates were able to write an appropriate equation of the line through BDBD, several did not express their answer in the required form ax+by+d=0ax+by+d=0, where aa, bb and dd are integers. Many final answers were given as y=13x+4y=13x+4 or y-13x-4=0y−13x−4=0. In part (d), writing the xx-coordinate of point DD was well done by most candidates. Some candidates wrote a coordinate pair rather than just the xx-coordinate as required.