coordinate geometry - lines

    Cards (10)

    • gradient formula
      y2y1/x2x1y2-y1/x2-x1
    • straight line equations
      y=y=mx+mx+cc or ax2+ax^2+bx+bx+c=c=00
    • equation to find equation of a line
      yy1=y-y1=m(xx1)m(x-x1)
    • find points where line meets x axis
      • make y=0
      • solve for x
    • find where line meets y axis
      • make x=0
      • solve for y
    • parralel lines
      have same gradient
    • perpendicular lines
      gradients are negative reciprocals of each other, multiply to make -1
    • midpoint of line formula
      [(x1+x2/2),(y1+y2/2)][(x1+x2/2),(y1+y2/2)]
      • mean of x and y values
    • length between two points
      • Pythagoras theorem
      • a2+a^2+b2=b^2=c2c^2 or squareroot(x2x1)2+square root(x2-x1)^2+(y2y1)2(y2-y1)^2
    • find intersection of lines
      • finding a point where x and y satisfies both equations
      • can solve by simultaneous equations, substituting one into the other or make equal to each other