Practice. Write the equation of a parallel line. -2 -3 M =-2 = 2 -3 3 Y-intercept M=2/3 and b is -1 so Write the equation of a line parallel to the line shown below and passing through point (1, 2) (1, 2) Step 2: Substitute into y = mx + b The slope is 2/3, the y-intercept is 1, so the equation of the parallel line is y=2/3x+1
Practice: Write the equation of a parallel line. Y-intercept M= 3 1 +3 +1 +3 +1 Y-intercept Substitute point (1,5) and the slope (3) into y=mx+b
Perpendicular Lines Lines that intersect at right angles are called perpendicular lines. The slopes of these lines are opposite reciprocals. Opposite reciprocals???? 3…..
Write the equation of a perpendicular line. Graph the lines. y=-2x+2 Y-intercept -2 +1 Y=1/2x+2
Flip the slope over and change the sign to the opposite. If the original slope is positive, the new one will be negative. If the original is negative, the new one will be positive.
Plug the new slope and the point (-1, 1) into y = mx +b +3 -7
Group Activity (click for answers) Y=2x+3 Y=2x-8 Y=-1/2x+8
Practice: Writing Equation of a Perpendicular Line +1 -3
Practice: Writing Equation of a Perpendicular Line