1. www.mathsrevision.com APP 1.1 www.mathsrevision.com NEW Higher Distance Formula The Midpoint Formula Prior Knowledge Collinearity Gradients of Perpendicular Lines Median, Altitude & Perpendicular Bisector Exam Type Questions m = tan θ Unit 1 Applications 1.1 Mindmap

2. Where is Straight Line Theory Used in Higher Recurrence Relations Circle Differentiation Logs & Exponentials Vector

3. Straight Line y = mx + c m = gradient c = y intercept (0,c) m = tan θ θ Possible values for gradient m > 0 m < 0 m = 0 m = undefined Distance between 2 points For Perpendicular lines the following is true. m 1.m 2 = -1 Parallel lines have same gradient Form for finding line equation y – b = m(x - a) (a,b) = point on line Terminology Median – midpoint Bisector – midpoint Perpendicular – Right Angled Altitude – right angled m 1.m 2 = -1

4. www.mathsrevision.com APP 1.1 Straight Line Facts Y – axis Intercept y = mx + c Another version of the straight line formula is ax + by + c = 0

5. www.mathsrevision.com APP 1.1 Questions Find the gradient and y – intercept for equations. (a) 4x + 2y + 10 = 0 (b) 3x - 5y + 1 = 0 (c) 4 - x – 3y = 0 m = -2 c = -5 m = 3/5 c = 1/5 m = - 1/3 c = 4/3 Demo

6. www.mathsrevision.com APP 1.1 = The Equation of the Straight Line The Equation of the Straight Line y – b = m (x - a) The equation of any line can be found if we know the gradient and one point on the line. O y x x - a P (x, y) m A (a, b) y - b x – a m = y - b (x – a) m Gradient, m Point (a, b) y – b = m ( x – a ) Point on the line ( a, b ) ax y b Demo

7. www.mathsrevision.com Higher Outcome 1 1-Aug-15www.mathsrevision.com 7 Gradient Facts m < 0 m > 0 m = 0 x = a y = c Sloping left to right up has +ve gradient Sloping left to right down has -ve gradient Horizontal line has zero gradient. Vertical line has undefined gradient.

8. www.mathsrevision.com Higher Outcome 1 1-Aug-15www.mathsrevision.com 8 Gradient Facts m > 0 Lines with the same gradient means lines are Parallel

9. www.mathsrevision.com APP 1.1 Straight Line Theory

10. www.mathsrevision.com APP 1.1 Straight Line Theory

11. www.mathsrevision.com APP 1.1 Straight Line Theory

12. www.mathsrevision.com APP 1.1 Straight Line Theory

13. www.mathsrevision.com APP 1.1 Find the equation of the straight line which is parallel to the line with equation and which passes through the point (2, –1). Find gradient of given line: Knowledge: Gradient of parallel lines are the same. Therefore for line we want to find has gradient Find equation: Using y – b =m(x - a) Typical Exam Questions

14. www.mathsrevision.com APP 1.1 Distance Formula Length of a straight line A(x 1,y 1 ) B(x 2, y 2 ) x 2 – x 1 y 2 – y 1 C x y O This is just Pythagoras’ Theorem

15. www.mathsrevision.com APP 1.1 Distance Formula The length (distance ) of ANY line can be given by the formula : Just Pythagoras Theorem in disguise Demo

16. www.mathsrevision.com APP 1.1 2√26 8√2 2√26 Isosceles Triangle ! Demo

17. www.mathsrevision.com APP 1.1 Mid-Point of a line A(x 1,y 1 ) B(x 2, y 2 ) x y O x 1 x 2 M y 1 y 2 The mid-point (Median) between 2 points is given by Simply add both x coordinates together and divide by 2. Then do the same with the y coordinates. Demo

18. www.mathsrevision.com APP 1.1

19. www.mathsrevision.com Higher Outcome 1 1-Aug-15www.mathsrevision.com 19 Straight Line Facts m = tan θ The gradient of a line is ALWAYS equal to the tangent of the angle made with the line and the positive x-axis θ θ O A H m = V H O A = O A tan θ = 0 o ≤ θ < 180 o Demo

20. www.mathsrevision.com APP 1.1 m = tan θ 60 o m = tan 60 o = √3

21. www.mathsrevision.com APP 1.1 m = tan θ y = -2x m = tan θ θ = tan -1 (-2) θ = 180 – 63.4 θ = 116.6 o

22. www.mathsrevision.com APP 1.1 Find gradient of the line: Use table of exact values Use Find the size of the angle a° that the line joining the points A(0, -1) and B(3  3, 2) makes with the positive direction of the x-axis. Exam Type Questions

23. www.mathsrevision.com APP 1.1 The line AB makes an angle of 60 o with the y-axis, as shown in the diagram. Find the exact value of the gradient of AB. Find angle between AB and x-axis: Use table of exact values Use (x and y axes are perpendicular.) Typical Exam Questions 60 o

24. www.mathsrevision.com APP 1.1 The lines and make angles of a  and b  with the positive direction of the x- axis, as shown in the diagram. a)Find the values of a and b b)Hence find the acute angle between the two given lines. Find supplement of b Find gradient of Find a° Find b° angle between two linesUse angle sum triangle = 180° 72° Typical Exam Questions 45 o 72 o 63 o 135 o

25. www.mathsrevision.com APP 1.1 Gradient of perpendicular lines If 2 lines with gradients m 1 and m 2 are perpendicular then m 1 × m 2 = -1 When rotated through 90º about the origin A (a, b) → B (-b, a) -a B(-b,a) -b A(a,b) a O y x Conversely: If m 1 × m 2 = -1 then the two lines with gradients m 1 and m 2 are perpendicular. -b Investigation Demo

26. www.mathsrevision.com Higher Outcome 1 A BC D 1-Aug-15 26 www.mathsrevision.com A Median means a line from a vertex to the midpoint of the base. Altitude means a perpendicular line from a vertex to the base. B D C Demo Demo

27. Higher Outcome 1 1-Aug-15 27 www.mathsrevision.com A B D C Perpendicular bisector - a line that cuts another line into two equal parts at an angle of 90 o Demo

28. Any number of lines are said to be concurrent if there is a point through which they all pass. For three lines to be concurrent, they must all pass through a single point. Demo

29. www.mathsrevision.com APP 1.1 Collinearity A C x y O x1x1 x2x2 B Points are said to be collinear if they lie on the same straight. The coordinates A,B C are collinear since they lie on the same straight line. D,E,F are not collinear they do not lie on the same straight line. D E F

30. www.mathsrevision.com APP 1.1 Straight Line Theory Since m PQ = m QR and they have a point in common Q PQR are collinear. D PQ =√2 D PQ =2√2 Ratio D PQ : D PQ 1:2

31. Finding the Equation of an Altitude A B To find the equation of an altitude: Find the gradient of the side it is perpendicular to ( ). m AB C To find the gradient of the altitude, flip the gradient of AB and change from positive to negative: m altitude = m AB –1 Substitute the gradient and the point C into y – b = m ( x – a ) Important Write final equation in the form A x + B y + C = 0 with A x positive. Common Straight Strategies for Exam Questions

32. Finding the Equation of a Median P Q To find the equation of a median: Find the midpoint of the side it bisects, i.e. O Calculate the gradient of the median OM. Substitute the gradient and either point on the line (O or M) into y – b = m ( x – a ) Important Write answer in the form A x + B y + C = 0 with A x positive. = = M ( ) M = 2 y 2 y 1 2 x 2 x 1, ++ Common Straight Strategies for Exam Questions

33. www.mathsrevision.com APP 1.1 Find the equation of the line which passes through the point (-1, 3) and is perpendicular to the line with equation Find gradient of given line: Find gradient of perpendicular: Find equation: Typical Exam Questions

34. www.mathsrevision.com APP 1.1 A and B are the points (–3, –1) and (5, 5). Find the equation of a)the line AB. b)the perpendicular bisector of AB Find gradient of the AB: Find mid-point of AB Find equation of AB Gradient of AB (perp): Use y – b = m(x – a) and point ( 1, 2) to obtain line of perpendicular bisector of AB we get Exam Type Questions

35. www.mathsrevision.com APP 1.1 A triangle ABC has vertices A(4, 3), B(6, 1) and C(–2, –3) as shown in the diagram. Find the equation of AM, the median from B to C Find mid-point of BC: Find equation of median AM Find gradient of median AM Typical Exam Questions

36. www.mathsrevision.com APP 1.1 P(–4, 5), Q(–2, –2) and R(4, 1) are the vertices of triangle PQR as shown in the diagram. Find the equation of PS, the altitude from P. Find gradient of QR: Find equation of altitude PS Find gradient of PS (perpendicular to QR) Typical Exam Questions

37. www.mathsrevision.com APP 1.1 Triangle ABC has vertices A(–1, 6), B(–3, –2) and C(5, 2) Find: a) the equation of the line p, the median from C of triangle ABC. b) the equation of the line q, the perpendicular bisector of BC. c) the co-ordinates of the point of intersection of the lines p and q. Find mid-point of AB Find equation of p Find gradient of p (-2, 2) Find mid-point of BC (1, 0) Find gradient of BC Find gradient of q Find equation of q Solve p and q simultaneously for intersection (0, 2) Exam Type Questions p q

38. www.mathsrevision.com APP 1.1 Triangle ABC has vertices A(2, 2), B(12, 2) and C(8, 6). a) Write down the equation of l 1, the perpendicular bisector of AB b) Find the equation of l 2, the perpendicular bisector of AC. c) Find the point of intersection of lines l 1 and l 2. Mid-point AB Find mid-point AC (5, 4) Find gradient of AC Equation of perp. bisector ACGradient AC perp. Point of intersection (7, 1) Perpendicular bisector AB Exam Type Questions l 1 l 2

39. www.mathsrevision.com APP 1.1 A triangle ABC has vertices A(–4, 1), B(12,3) and C(7, –7). a) Find the equation of the median CM. b) Find the equation of the altitude AD. c) Find the co-ordinates of the point of intersection of CM and AD Mid-point AB Equation of median CM using y – b = m(x – a) Gradient of perpendicular AD Gradient BC Equation of AD using y – b = m(x – a) Gradient CM (median) Solve simultaneously for point of intersection (6, -4) Exam Type Questions

40. www.mathsrevision.com APP 1.1 A triangle ABC has vertices A(–3, –3), B(–1, 1) and C(7,–3). a) Show that the triangle ABC is right angled at B. b) The medians AD and BE intersect at M. i) Find the equations of AD and BE. ii) Find find the co-ordinates of M. Gradient AB Product of gradients Gradient of median ADMid-point BCEquation AD Gradient BC Solve simultaneously for M, point of intersection Hence AB is perpendicular to BC, so B = 90° Gradient of median BE Mid-point AC Equation AD Exam Type Questions M

41. Straight Line y = mx + c m = gradient c = y intercept (0,c) m = tan θ θ Possible values for gradient m > 0 m < 0 m = 0 m = undefined Distance between 2 points For Perpendicular lines the following is true. m 1.m 2 = -1 Parallel lines have same gradient Form for finding line equation y – b = m(x - a) (a,b) = point on line Terminology Median – midpoint Bisector – midpoint Perpendicular – Right Angled Altitude – right angled m 1.m 2 = -1

42. www.mathsrevision.com APP 1.1 Are you on Target ! Update you log book Make sure you complete and correct ALL of the Straight Line questions inStraight Line the past paper booklet.