(adsbygoogle = window.adsbygoogle || []).push({}); M1.m2 = -1 ??

Why is the product of the gradients of 2 straight line perpendicular to each other is always equal to -1 ?? Is there any theory to explain this ??

**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!

# M1.m2 = -1 ?

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