quick question

how is cos pi/6 = sq root 3 /2 I just can`t work it out

DL

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- September 30th 2012, 03:24 PMdavellew69cos pi/6
quick question

how is cos pi/6 = sq root 3 /2 I just can`t work it out

DL - September 30th 2012, 03:52 PMskeeterRe: cos pi/6
are you familiar w/ the side ratios of a 30-60-90 triangle? if so, let the hypotenuse have length = 1. also ...

- October 8th 2012, 05:14 AMStefanTMRe: cos pi/6
Hi Skeeter,

a little correction:

you did write tan(tau),

cos(tau) = adjacent side / hypotenuse - October 8th 2012, 06:36 AMskeeterRe: cos pi/6
yes, my error ... had tangent on the brain

- October 8th 2012, 07:18 AMSorobanRe: cos pi/6
Hello, davellew69!

Quote:

Consider an equilateral triangle with side length 2.

Each vertex has a 60^{o}angle.

Draw an altitude . .It bisects the angle.

The diagram looks like this.

Code:`A`

*

/|\

/ | \

/30| \

2 / |h \ 2

/ | \

/ | \

/ 60 | \

B *-------*-------* C

1 D 1

From which we get: .

Hence, in a 30-60 right triangle, we have these sides:

. .

Now we can write all the trig values for 30^{o}and 60^{o}.