# Mathematics the cross product of perpendicular vectors

Hey! Trying to do this maths question but completely stuck on how to prove that it is false algebraically? The question is:
a is perpendicular to b therefore a x b = 0 and I need to prove that if a and b are perpendicular then the cross products of them do not equal 0.
Thank you so much!
Original post by Shivi8
Hey! Trying to do this maths question but completely stuck on how to prove that it is false algebraically? The question is:
a is perpendicular to b therefore a x b = 0 and I need to prove that if a and b are perpendicular then the cross products of them do not equal 0.
Thank you so much!

Can you post the original question(s). Have you covered the magnitude formula |a||b|sin(theta)?
Original post by mqb2766
Can you post the original question(s). Have you covered the magnitude formula |a||b|sin(theta)?

Its the first one on the second column and we've been asked to prove if they're true or false using algebra or reason, not using numbers. And yep I have covered the magnitude formula
Original post by Shivi8
Its the first one on the second column and we've been asked to prove if they're true or false using algebra or reason, not using numbers. And yep I have covered the magnitude formula

Youll need to upload the file.
Ah its not letting me upload it sorry! All the question says though is:
a is perpendicular to b therefore a x b = 0
Prove whether this statement is true or false using algebra or another non-numerical method.
(edited 1 year ago)
Original post by Shivi8
Ah its not letting me upload it sorry! All the question says though is:
a is perpendicular to b therefore a x b = 0
Prove whether this statement is true or false using algebra or another non-numerical method.

You could do it using the magnitude of the result and a simple argument about each of the terms. But there are a few ways you could go. A simple counter example would be another way.
(edited 1 year ago)
Oh perfect thank you so so much!