trig help

**SirNostalgic** · March 23rd 2009, 12:23 PM

In my work they are asking for the exact values of $\frac{\Pi}{8}$ in all forms: Sin, Cos, Tan and recipricols by using double angle formula's. Sin and Cos of $\frac{\Pi}{8}$ make sense but i have a query involving Tan and Cotan.

i have figured out that $sin\frac{\Pi}{8} = \frac{-\sqrt2+2}{2}$

i have also figured out that $cos\frac{\Pi}{8} = \frac{\sqrt2+2}{2}$

How would i go about figuring out $Tan\frac{\Pi}{8}$ , Using the respective double angle formula didn't work so now i am stumped. Also i don't know at which point i should switch the numerator and denominator for Recipricol functions

$Cosec(\frac{\Pi}{8}) = \frac{1}{Sin\frac{\Pi}{8}}$

$= \frac{1}{\frac{-\sqrt2+2}{2}} = \frac{2}{-\sqrt2+2}$ and times by the conjugate to get the answer?

any help would greatly boost my confidence

**mr fantastic** · March 23rd 2009, 12:28 PM

Originally Posted by SirNostalgic

In my work they are asking for the exact values of $\frac{\Pi}{8}$ in all forms: Sin, Cos, Tan and recipricols by using double angle formula's. Sin and Cos of $\frac{\Pi}{8}$ make sense but i have a query involving Tan and Cotan.

i have figured out that $sin\frac{\Pi}{8} = \frac{-\sqrt2+2}{2}$

i have also figured out that $cos\frac{\Pi}{8} = \frac{\sqrt2+2}{2}$

How would i go about figuring out $Tan\frac{\Pi}{8}$ , Using the respective double angle formula didn't work so now i am stumped. Also i don't know at which point i should switch the numerator and denominator for Recipricol functions

$Cosec(\frac{\Pi}{8}) = \frac{1}{Sin\frac{\Pi}{8}}$

$= \frac{1}{\frac{-\sqrt2+2}{2}} = \frac{2}{-\sqrt2+2}$ and times by the conjugate to get the answer?

any help would greatly boost my confidence

The sine one is done here. But you only need to get one of sine or cos using the double angle formula - all the others can be got using the Pythagorean Identity.

**SirNostalgic** · March 23rd 2009, 12:50 PM

so since Sin = O/H i should put those values on a triangle and use pythagoras to figure out the adjacent?

and this should give me the values of the rest?

Thread: trig help

LinkBack

Thread Tools

Display

trig help

Similar Math Help Forum Discussions

Compute Trig Function Values, Solve Trig Equation

A few trig problems- help please (double angle and simplifying trig expressions)

Trig ratios, other trig mapping questions :/ Help greatly appreciated

Another question proving that a trig equation follows from another given trig equatio

Trig Equations with Multiple Trig Functions cont.

Search Tags