Hey CPhill, how do you answer like 90% of all questions possible?

because sin[x] = sin[360-x]

you could say that 1/2*10 is 5 for a, 1/2*100 is 50 for b, and for c, more tests gives a higher accuracy rate, so most likely b - although there is no guarentee, because as you know, low chance doesn't mean impossible!

i would say it couldn't be 2, as one side would be more than 1/2 of the whole perimeter, so it must be 3

Well, DEB is isoceles, so EB=3. then, i don't know what to do, but i have a feeling that be and ad are angle bisectors, but i can't prove it???

You could use pascal's triangle and find out what it is, looking at the first or last 6 numbers in the 13th row, including the ones at the top, add them together, and substract that from 2^12

For a, you can find that you have to choose 2 from each row, making (4 choose 2)^4, which is 1296

For b, it is the same, except it is 4 choose 3, making it 4^4=256 if i am not mistaken