1. Geometry
Today:
Check Up
3.4 Instruction
Practice
Never discourage anyone who continually makes progress… no matter how slow.
Plato

2. Chapter 3 Check Up
For 1 – 3, refer to the figure.

3. 3.4 Equations of Lines Objectives: Vocabulary: Find the slope of lines
Find slope of parallel and perpendicular lines
Find equations of lines using y = mx + b
Find equations of lines using y – y1 = m(x – x1)
Write the equation of parallel lines
Vocabulary:
slope, slope intercept form, point-slope form

4. 3.3 Slopes of Lines Formula: Slope rules: Parallel Lines:
Perpendicular Lines:
Parallel Lines: same slope
opposite reciprocal slope
0 slope: horizontal line
y = #
Undefined slope: vertical line
x = #

5. 3.4 Equations of Lines y-intercept (0, b) slope Formulas:
slope-intercept form
y-intercept
(0, b)
slope
Need slope (m) to find parallel and perpendicular from equation.

6. Are these lines parallel, perpendicular or neither?

7. Are these lines parallel, perpendicular or neither?
y = 3x – 6 y = 3x+ 4
y = 1/5x y = 5x – 1/4
4y = 8x + 12 y = -1/2 x + 4
Perpendicular
Need slope (m) to find parallel and perpendicular from equation.

8. slope y - y1=m(x - x1) point (x1, y1)
Formulas:
point-slope form
slope
y - y1=m(x - x1) y1 x1
point (x1, y1)
Used to find the equation of a line
find slope, m, and a point (x1, y1)
plug values into the equation
distribute and add

9. y – 5 = 3 (x - 2) y - y1=m(x - x1) x1 y1 x1 y1 m x1 y1 Perp m m = +½
Find the equation of the line through (2, 5) and m = 3.
y – 5 = 3 (x - 2)
y - y1=m(x - x1) x1 y1
Still distribute and add
Find the equation of the line through (0, 3) and parallel to y = 3x + 9.
Find the equation of the line through (4, -1) and perpendicular l to y = -2x – 1. x1 y1 m x1 y1
Perp m
m = +½

10. Are the 2 lines parallel, perpendicular, or neither?
y = -2/3 x – 3
y = 2/3x + 5
3y + 4x = 24
4y – 3x = 12
4y + 3x = 15
12x + 9y = 36
Perp

11. Find the equation of the line through (4, 5) and m = 6.
Find the equation of the line through (3, 7) and parallel to line from #1.
Find the equation of the line through (-2, 4) and perpendicular to line from #1.
Find the equation of the line through (-2, 4) and perpendicular to line y = 2x -7.

12. Yesterday Assignment:
3.4 p. 203 #37-55 odd, all
Never discourage anyone who continually makes progress… no matter how slow.
Plato