cos pi/6

quick question

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

DL

are you familiar w/ the side ratios of a 30-60-90 triangle? if so, let the hypotenuse have length = 1. also ...

Hi Skeeter,

a little correction:
you did write tan(tau),

cos(tau) = adjacent side / hypotenuse

yes, my error ... had tangent on the brain

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

---

Pythagorus says: .

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.