The functions are
and
.
The functions is
.
Differentiate on each side with respect to
.




The slope
.
The function is
.
Rewrite the function
.
Apply derivative on each side wih respect to
.

Quotient rule of the derivative:
.



The slope
.
Two functions are orthogonal when
.
Substitute
and
in the above equation.

Hence the two functions are orthogonal.
\The functions are
and
.
Consider
and
.
and
.
and
.
Graph :
\Graph the two polynomials
and
.

Observe the graph :
\The tangent line to the curve are orthogonal to each other.
\The functions are
and 
Consider
and
.
and 
and
.
Graph:
\Graph the two polynomials
and
.

Observe the graph :
\The tangent line to the curve are orthogonal to each other.
\The curve
and
are orthogonal to each other.