Straight line

• Gradient = $\frac{y_2-y_1}{x_2-x_1}$
• gradient = $\tan\theta$
• equation of straight line

  y=mx-c

  y-b=m(x-a)
• distance

  $c^2=$$a^2+$$b^2$

  $\left(AB\right)^2=$$\left(x_2-x_1\right)^2-\left(y_2-y_1\right)^2$

  $AB=$$\sqrt{\left(x_2-x_1\right)^2-\left(y_2-y_1\right)^2}$
• Midpoint = $\left(\frac{x_1+x_2}{2},\frac{y_1+y_2}{2}\right)$
• Median

  step 1: midpoint = $\left(\frac{x_1+x_2}{2},\frac{y_1+y_2}{2}\right)$

  step 2: gradient = $\frac{y_2-y_1}{x_2-x_1}$

  step 3: y-b=m(x-a)
• Altitude (Perpendicular)

  step 1: gradient = $\frac{y_2-y_1}{x_2-x_1}$

  step 2: perpendicular gradient (m2)

  step 3: y-b=m(x-a)
• Perpendicular Bisector

  step 1: gradient = $\frac{y_2-y_1}{x_2-x_1}$

  step 2: m2

  step 3: midpiont = $\left(\frac{x_1+x_2}{2},\frac{y_1+y_2}{2}\right)$

  step 4: y-b=m(x-a)