Perpendicular lines

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Chapter 5 - Coordinate Geometry
Objectives
To find the gradient of lines perpendicular to
each other.
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Finding the Midpoint
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2
3
6
5
4
9
8
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(Were going to use this later)
Starter
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These lines are perpendicular
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PERPENDICULAR MEANS AT RIGHT ANGLES
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What is each gradient?
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2
Gradient ½
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Gradient -2
1
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What is each gradient?
Gradient 3
1
3
3
1
Gradient -1/3
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THE GRADIENT OF A PERPENDICULAR LINE IS
THE NEGATIVE RECIPROCAL OF THE OTHER
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What is the gradient of the lines perpendicular
to these?
y 2x 1
m 2
-1/m -1/2
y 2 4x
m 4
-1/m -1/4
y 3x 2
m 3
-1/m -1/3
y 2x 2
m -2
-1/m 1/2
2y 3x - 2
m 3/2
-1/m -2/3
5y 2x 3
m -2/5
-1/m 5/2
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Write down an equation of a line perpendicular to
these
y 2x 1
y 2 4x
y 3x 2
y 2x 2
2y 3x - 2
5y 2x 3
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THE PRODUCT OF GRADIENTS OF PERPENDICULAR LINES
IS EQUAL TO -1
Exercise 5E Question 1
11
Two points A(1,2) and B(-3,6) are joined to make
the line AB. Find the equation of the
perpendicular bisector of AB