exact trig values cos mnemonic

How do you remember all the follow cos values:

To remember the values of the key angles for cos, use the following mnemonic or hand trick:

First assign all the fingers on one hand using zero to ninety with the thumb sticking up, as follows:

For any sine of an angle, square root the number of fingers BELOW and divide by 2.

Use the formula:

And count the number of fingers ABOVE.

`cos 0° =``(√4)/2``=(2)/2``=1`

`cos 30° =``(√3)/2`

`cos 45° =``(√2)/2`

`cos 60° =``(√1)/2``=(1)/2`

`cos 90° =``(√0)/2``=0`