Let a be the point of the tangent line then

is a point on the graph

So the slope at point a is

Now we can find the equation of the line through the point

We can now find the x and y intercepts of the equation of the line

and

These are the lengths of the base and height of the triangle

So its area is

setting each factor equal to zero and solving gives a=1 or a=-1

since we want the part in the first quadrant we don't use a=-1

Yeah!!!