2.3 Equations of Lines

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2.3 Equations of Lines

• Going the other direction from a picture to the
  equation

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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
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So, what do you need to have to find the equation
of the line?

• Slope and

• a point

Lets try one Slope2 and the y-int 5
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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)
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1. 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!
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Other Review Items
Altitude Median Perpendicular bisector
MP
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• Triangle ABC has vertices A(-4,-2) L(2,8)
  G(6,2)
• Write the equation of AL
• Find the Slope

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• 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
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• 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
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Group Problem

• Find the distance between (0,4) and (3,0)