The shortest distance between the lines $${{x - 1} \over 2} = {{y + 8} \over -7} = {{z - 4} \over 5}$$ and $${{x - 1} \over 2} = {{y - 2} \over 1} = {{z - 6} \over { - 3}}$$ is :
Let $$f$$ and $$g$$ be the twice differentiable functions on $$\mathbb{R}$$ such that
$$f''(x)=g''(x)+6x$$
$$f'(1)=4g'(1)-3=9$$
$$f(2)=3g(2)=12$$.
Then which of the following is NOT true?
A circle with centre (2, 3) and radius 4 intersects the line $$x+y=3$$ at the points P and Q. If the tangents at P and Q intersect at the point $$S(\alpha,\beta)$$, then $$4\alpha-7\beta$$ is equal to ___________.
A triangle is formed by the tangents at the point (2, 2) on the curves $$y^2=2x$$ and $$x^2+y^2=4x$$, and the line $$x+y+2=0$$. If $$r$$ is the radius of its circumcircle, then $$r^2$$ is equal to ___________.