A very simple and noob question, sorry for this.(adsbygoogle = window.adsbygoogle || []).push({});

Looking at http://en.wikipedia.org/wiki/Perpendicular I found that two lines are perpendicular if and only if the product of their slopes is -1.

If I have two lines described by the following equations:

y = ax + b

g = cx + d

then they're perpendicular if ac = -1 right? Okay...

What's the explanation for this? How do I conclude that they're only perpendicular if and only if the product of their slopes is -1?

Just another little question: the slope of a line is the tangent of the angle between the line and the x-axis? that's right?

Thank you

**Physics Forums - The Fusion of Science and Community**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Perpendicular lines

Loading...

Similar Threads - Perpendicular lines | Date |
---|---|

I Why on Earth's surface, longitudinal or merediance lines are perpendicular to equatorial line? | Apr 12, 2016 |

Skew and perpendicular lines? | Oct 22, 2015 |

Mapping 3D point to cone surface using perpendicular line | Oct 15, 2014 |

Slope of the perpendicular line on the other line | Apr 9, 2014 |

Perpendicular lines | Jan 26, 2004 |

**Physics Forums - The Fusion of Science and Community**