Math  Vectors
posted by Shaila on .
Prove that vector i,j and k are mutually orthogonal using the dot product.
What is actually meant by mutually orthogonal?

mutually orthogonal=the three of them are orthogonal (or perpendicular) to each other,, [angle between them is 90 degrees]
first recall the formula for the dot product. for any given vectors A and B,
A(dot)B=ABcos(theta)
where A and B are the magnitude of vectors A and B respectively
*note: magnitude means you get the squareroot of the sum of the squares of each element in the given vector.
example, the vector <1,2,4> has a magnitude of squareroot of (1^2+(2)^2+4^2) or squareroot of 21
*note: A(dot)B is the sum of the products of the respective elements (x, y and z elements) of two given vectors [this is scalar]
example, A<2,1,3> and B<3, 2, 0>
A(dot)B = 2*3 + 1*2 + 3*0 = 8
going back to your question,
i<1,0,0> ; i=1
j<0,1,0> ; j=1
k<0,0,1> ; k=1
note that i(dot)j is zero, as well as i(dot)k and j(dot)k,,
therefore in the equation, A(dot)B=ABcos(theta)
cos(theta) is equal to zero (since 0/1=0)
therefore, theta you will get is 90 degrees (for i(dot)j, i(dot)k and j(dot)k), which means they are mutually orthogonal to each other,,
so there,, i'm sorry for long explanation..