don steward
mathematics teaching 10 ~ 16

Thursday, 21 January 2016

sector angles

it seems that it was the Babylonians who established the (arbitrary) idea that there are 360 degrees in a whole turn, linked to their base 60 arithmetic

there was an attempt to change this (in France) to 400 gradians (grads) to create a metric measure

once 360 degrees is established, the various fractions can be determined

this work is intended to be quick and, ideally, mental
what are the angles shown?

my apologies, the images that these are based on came from someone else
I failed to make a note of the source and couldn't find it again ... (?)

more (mental) work can focus on angles between numbers on the clock face and between the compass points

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