Use the dot product to determine whether v and w are orthogo

Use the dot product to determine whether v and w are orthogonal v = 2i + 8j and w = 4i - j

v=2i+ 8j and w=4i-j

v.w= I V I I W I cos theta

v.w= 2*4 + 8*(-1)=0

I V I =sqrt(2^2 + 8^2)= sqrt 68

I W I=sqrt(4^2 + (-1)^2)=sqrt17

0=sqrt68 * sqrt 17 cos theta

cos theta=0/ sqrt 68 * sqrt 17=0

theta=90

Since the angle is 90 degree,therefore they are orthagonal