Parallel & Perpendicular Gradients (Edexcel AS Maths): Revision Note
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Parallel & Perpendicular Gradients
What are parallel lines?
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Parallel lines are equidistant meaning they never meet
Parallel lines have equal gradients
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What are perpendicular lines?
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Perpendicular lines meet at right angles
The product of their gradients is -1
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What are collinear lines?
Collinear lines are two line segments that are part of the same line
They have equal gradients and pass through, or meet at, a point
Rearrange their equations into the same form and they will be identical
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How do I tell if lines are parallel or perpendicular?
Rearrange equations into the form y = mx + c
m is the gradient
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Examiner Tips and Tricks
Exam questions are good at “hiding” parallel and perpendicular lines.
For example a tangent and a radius are perpendicular.
Parallel lines could be implied by phrases like “… at the same rate …”
Worked Example
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