Math Is Fun Forum

[Problem uploaded as Jpeg]

I looked for similar triangles to try and solve this. I got:

So:

So the area of the circle would be:

This doesn't come up in the answers however, can someone correct me please.

I watched a documentary on nuclear weapons yesterday in Physics, and it was all rather interesting. Later I went online to do some further research on nuclear weapons, and found out a lot about Mutually Assured Destruction (MAD). It is basically when two countries have the firepower to kill each other in one blow. If one attacks the other, the other will strike back and both sides will be totally destroyed.
The thing is, with nuclear weapons, not only are both sides destroyed, but the nuclear fallout would induce a worldwide nuclear winter, something which no life can survive.

We have come extremely close to wiping out all humanity in the past, a prime example being Stanislav Petrov. An equipment error with missile detection systems led to the false belief that America had sent a nuke over to Russia. Petrov, a lieutenant colonel at the time, refused to believe that it was true, and hence didn't inform the Russian government to retaliate. It's amazing how one person, who has his finger over the red button, can, in a split second, save the world, or destroy it.

The worrying thing is that with over 25,000 nuclear weapons in the world today, it is still possible that MAD could come into effect at any time. And in the future, even when we expand to other planets, it is worrying how humanity could wipe out thousands of years of humanity, in a single, final decision.

Do you think we will always have to fear MAD?

Hey I was wondering if someone could write an article on how to write a mathsisfun quality article? Then perhaps more of us could contribute and help out Mathsisfun.

After all, it would be easy to just create another math page on determinants... or factorising... but mathsisfun pages are far better at explaining things.