AP problem, huh?
tangent line has equation ...
y - (6 - w<sup>2</sup>) = -2w(x - w)
the line's x-intercept is where y = 0 ...
w<sup>2</sup> - 6 = -2w(x - w)
solve for the x-intercept in terms of w
the line's y-intercept is where x = 0 ...
y - (6 - w<sup>2</sup>) = -2w(-w)
solve for the y-intercept in terms of w
now, the area of the triangle is A = (1/2)(x-intercept)(y-intercept)
can you finish?