# Find so that these vectors are mutually perpendicular

• March 30th 2011, 03:08 AM
realistic
Find so that these vectors are mutually perpendicular
Find c so that these vectors are mutually perpendicular:
a = <c,−2, 3> and b = <c, c,−5>.

how would you go about doing this.

I know how to apply the cross product.
• March 30th 2011, 03:10 AM
Prove It
Two vectors are perpendicular if their dot product is $\displaystyle 0$.
• March 30th 2011, 03:19 AM
realistic
thanks for response and yes i agree if its 0 its mutually perpendicular.

would i have to put a = <c,−2, 3> and b = <c, c,−5> into its determinant form then solve?
• March 30th 2011, 03:30 AM
Prove It
No, take the dot product and set it equal to $\displaystyle 0$. Then solve the resulting quadratic.
• March 30th 2011, 03:48 AM
realistic
ok i see

i got an answer of −3 or it could be 5 i think that's correct
• March 30th 2011, 04:34 AM
Plato
Yes that is correct.