zondag 17 september 2017
vrijdag 15 september 2017
Mooie opgave ruimtemeetkunde
Construeer een vlak V welke gaat door het punt P (dat op BT ligt), zo dat de doorsnede van V met piramide T.ABCD een parallellogram is.
vrijdag 8 september 2017
Brain Damage - Pink Floyd
The lunatic is on the grass
The lunatic is on the grass
Remembering games and daisy chains and laughs
Got to keep the loonies on the path
The lunatic is in the hall
The lunatics are in my hall
The paper holds their folded faces to the floor
And every day the paper boy brings more
And if the dam breaks open many years too soon
And if there is no room upon the hill
And if your head explodes with dark forebodings too
I'll see you on the dark side of the moon
The lunatic is in my head
The lunatic is in my head
You raise the blade, you make the change
You re-arrange me 'til I'm sane
You lock the door
And throw away the key
There's someone in my head but it's not me
And if the cloud bursts, thunder in your ear
You shout and no one seems to hear
And if the band you're in starts playing different tunes
I'll see you on the dark side of the moon
The lunatic is on the grass
Remembering games and daisy chains and laughs
Got to keep the loonies on the path
The lunatic is in the hall
The lunatics are in my hall
The paper holds their folded faces to the floor
And every day the paper boy brings more
And if the dam breaks open many years too soon
And if there is no room upon the hill
And if your head explodes with dark forebodings too
I'll see you on the dark side of the moon
The lunatic is in my head
The lunatic is in my head
You raise the blade, you make the change
You re-arrange me 'til I'm sane
You lock the door
And throw away the key
There's someone in my head but it's not me
And if the cloud bursts, thunder in your ear
You shout and no one seems to hear
And if the band you're in starts playing different tunes
I'll see you on the dark side of the moon
zondag 3 september 2017
World view
Somewhat like Eratosthenes, the Iranian polymath Al-Biruni (973-1048) was able to estimate the radius of the earth using just a few measurements and some clear thinking. If h is a mountain with a known height and the distance from the mountaintop A to the horizon C can be established accurately, then angle α is the same as angle AOC at the earth’s center and we have everything we need to calculate leg OC of right triangle AOC, which is the radius of the earth.
Biruni carried this out using a tall mountain near Nandana in present-day Pakistan. He estimated the earth’s radius at 6,339.9 km, which is only 16.8 km less than the current value of 6,356.7 km. This accuracy would not be obtained in the West until the 16th century.
