1. Going the other direction – from a picture to the equation
2.3 Equations of Lines
Going the other direction – from a picture to the equation

2. There are 3 standard forms of equations
Slope intercept form
y = mx + b
Standard form
Ax + By = C
A, B and C are integers and A is positive
3. Point slope form
y intercept
slope

3. So, what do you need to have to find the equation of the line?
Slope and
a point
Lets try one:
Slope=2 and the y-int = 5

4. Find the equation of the line that has points of (0,3) and (4,0)
Slope = 3, x intercept = 10
Slope = 3, passes through (10, 10)

5. Parallel to -4x + 2y = 10 and passes through (-1, -1)
7. Parallel to x + 2y = 1 and passes through the point of intersection of the lines y = 3x – 2 and y = 2x + 1.
Solve systems of equations to get point!

6. Other Review Items
Altitude
Median
Perpendicular bisector MP

7. Triangle ABC has vertices A(-4,-2) L(2,8) G(6,2)
Write the equation of AL
Find the Slope:

8. Triangle ABC has vertices A(-4,-2) L(2,8) G(6,2)
Find the equation of the perpendicular bisector
of LG.
Steps:
Find MP of LG (avg x, avg y)
Find the slope of LG and
take neg reciprocal
3. Plug in MP to find b L G A

9. Triangle ABC has vertices A(-4,-2) L(2,8) G(6,2)
Find the equation of the altitude to AG
Steps:
Find the slope of AG and
take neg reciprocal
2. Plug in point L to find b L G A

10. Group Problem:
Find the distance between (0,4) and (3,0):