Consider and
are two non zero vectors.
(a)
\Scalar projection of onto
is
.
Scalar projection of onto
is
.
The condition is possible when
.
is when
.
The Scalar projection of onto
is equal to the Scalar projection of
onto
is possible when the magnitude of
is equal to the magnitude of
or when
and
are orthogonal.
(b)
\When or if the two vectors are orthogonal then the condition
is possible.
If and
are perpendicular and do not have the same length and the equation still holds then
is possible.
(a) is when
.
(b) is possible when
.