P ARALLEL & P ERPENDICULAR L INES IN COORDINATE G EOMETRY What types of slopes do parallel lines have? What types of slopes do perpendicular lines have?

Parallel lines have the same slope. Perpendicular lines have slopes that are opposite reciprocal.

A NSWER THE FOLLOWING QUESTIONS WITH YOUR GROUP MEMBERS What is the slope of a line parallel to y = 3x – 7? What is the slope of a line perpendicular to y = -2x + 6? What is the slope of a line parallel to y = 9? What is the slope or a line perpendicular to y = -x/5 + 11

Find the equation of a line that is parallel to the line y = -7x + 4 and passes through the point (-4, 6)

STEP ONE Identify the slope and point Slope is -7 Point is (-4, 6) If we have a point and a slope, what form of an equation do we need to use?

STEP TWO Plug into point – slope form y – y 1 = m(x – x 1 ) y – 6 = -7(x – -4)

STEP THREE Finish by putting equation into slope-intercept form y – 6 = -7(x – -4) y – 6 = -7(x + 4) y – 6 = -7x – 28 y = -7x – 22

Find the equation of a line that is perpendicular to the line y = 3x – 9 and passes through the point (-1, 8)

STEP ONE Identify the slope and point Slope is Point is (-1, 8) If we have a point and a slope, what form of an equation do we need to use?

STEP TWO Plug into point – slope form y – y 1 = m(x – x 1 ) y – 8 = (x – -1) y – 8 = x –

STEP THREE Finish by putting equation into slope-intercept form y – 8 = (x – -1) y – 8 = (x + 1) y – 8 = x – y = x +

TRY ON YOUR OWN!!! Find the equation of a line that is perpendicular to the line y = -2x – 9 and passes through the point (-4, 6) Find the equation of a line that is parallel to the line y = 3x + 5 and passes through the point (-9, 1)

TIME TO PROCESS WHAT YOU LEARNED THINK TO YOURSELF!!! Think of a three word statement that sums up something you learned from this lecture. DO NOT SAY IT OUT LOUD!!! We will go around the room and share in two minutes