# Slope The slope of a line is how

• Slides: 11

Slope – The slope of a line is how much the line changes vertically over how much the line changes horizontally. Slope – The slope of a line blah argle bargle SLOPE = m = y Change in x = rise = run Wise guys X - men Find the slope of this line -1 SLOPE = m = 3 x Slope: positive, negative? NEGATIVE, it’s going down! Also, negative number!!

SLOPE FORMULA!! MEMORIZE!! SLOPE = m = y 2 – y 1 Find points (1, 0) (4, -1) and label x 1 y 1 x 2 y 2 x 2 – x 1 y Plug into formula y -12 y 01 x 42 x 11 Reduce Fraction -1 3 -1 SLOPE = m = 3 x

SLOPE FORMULA!! MEMORIZE!! SLOPE = m = y 2 – y 1 x 2 – x 1 Slope: positive, negative? Find points (-2, -1) (2, 5) and label x 1 y 1 x 2 y 2 Plug into formula POSITIVE!!! It’s going up, slope is also positive! Reduce y Fraction x y 52 y-11 x 22 x-21 6 4 3 2 SLOPE = m = 6 4 3 2

SLOPE = m = y 2 – y 1 y x 2 – x 1 Find the slope, and say if it positive, negative, zero, or undefined! UNDEFINED – VERTICAL NEGATIVE ZERO HORIZONTAL SLOPE, ZERO ON SLOPE IS ZERO! DENOMINATOR!!!! x

x 1 y 1 x 2 y = 5 We need to find the unknown variable. I want you to try to figure it out. You can use the slope formula, or graph. Five minutes of silently working on it.

x 1 y 1 x 2 y 2 We need to find the unknown variable. Plug into the slope formula. Simplify Cross-multiply and solve SOLVE-TASTIC!!

x 1 y 1 x 2 y 2 We need to find the unknown variable. Plug into the slope formula. Simplify Cross-multiply and solve Why do we need to use the formula instead of always drawing the picture?

Parallel and Perpendicular Lines SAME Parallel Lines have the ______ slope Blue Green What do you notice about the lines and the slope? Lines are perpendicular Slopes are opposite reciprocals, or slopes multiply to equal -1

• Theorem 13 -3 – Two nonvertical lines are parallel if and only if their slopes are equal • Theorem 13 -4 – Two nonvertical lines are perpendicular if and only if the product of their slope is -1.

Parallel Lines, SAME SLOPE Perpendicular Lines, opposite reciprocal. Slope Parallel Perpendicular

• T - HW #52: Pg 532 WE: 7— 11, 18— 25, 30— 31; Pg 537: 5— 9 • I will be here at lunch or after school (unless I am wii hunting)