**Q-a**Write down the exact values of sin (pie/3) and cos (pie/3.

**b**If tan x= 4sin (pie/3) cos (pie/3).

Find exact values of x for x for 0<= x <= 2 pie

Posted 07 September 2005 - 04:05 PM

wasting my time no not really

that diagram gives you the corresponding number for the angles 45[deg], 30[deg] and 60[deg]

to work out the answer use trigonometry

so from them cos 60 would be 1/root3

if you can see that?!

And use the sine and cosine curves for the rest of the basic ones

sine

cosine

you can find out from these two where the main angles are

so from the first graph you can see that sin180 is 0

Its very comlicated to describe it

oh and can you convery angles into radians?!

that diagram gives you the corresponding number for the angles 45[deg], 30[deg] and 60[deg]

to work out the answer use trigonometry

so from them cos 60 would be 1/root3

if you can see that?!

And use the sine and cosine curves for the rest of the basic ones

sine

cosine

you can find out from these two where the main angles are

so from the first graph you can see that sin180 is 0

Its very comlicated to describe it

oh and can you convery angles into radians?!

**Edited by dondon, 07 September 2005 - 04:20 PM.**

Posted 07 September 2005 - 08:58 PM

b.)

Tan x = 4 Sin ( /3 ) Cos ( /3 ) for ( 0 x 2 )

Tan x = 4 * ( 3 /2 ) * 0.5

Tan x = 3 x = Tan inverse 3

So, x is the tan inverse of 3, which gives you ( /3) for your first value. Now remember: because the value of X can lie anywhere between 0 and 2 , you've also got to check elsewhere where Tan is positive. If you look to your 'CAST' diagram, you'll see Tan is also positive in the fourth quadrant (presuming your first quadrant is C, then A, then S, then T.), and for the 4th quadrant, you add your value to , so the other value of x is [ + ( / 3 ) ] = 4 / 3

x = ( /3 ), (4 /3)

ps: If you don't follow in terms of radians, convert it to degrees - it's MUCH easier to see. Once you get used to radians, you'll grow comfortable with them. Also, do try to get used to using the BBCode for symbols such as Pi, Theta, Root e.t.c. (you can find it in the smilies pop up window, and it used to be on Ally's sig.. not too sure whether it's still there lol.) But yeah, it makes the question much easier to read and get accross. Cheers.

Tan x = 4 Sin ( /3 ) Cos ( /3 ) for ( 0 x 2 )

Tan x = 4 * ( 3 /2 ) * 0.5

Tan x = 3 x = Tan inverse 3

So, x is the tan inverse of 3, which gives you ( /3) for your first value. Now remember: because the value of X can lie anywhere between 0 and 2 , you've also got to check elsewhere where Tan is positive. If you look to your 'CAST' diagram, you'll see Tan is also positive in the fourth quadrant (presuming your first quadrant is C, then A, then S, then T.), and for the 4th quadrant, you add your value to , so the other value of x is [ + ( / 3 ) ] = 4 / 3

x = ( /3 ), (4 /3)

ps: If you don't follow in terms of radians, convert it to degrees - it's MUCH easier to see. Once you get used to radians, you'll grow comfortable with them. Also, do try to get used to using the BBCode for symbols such as Pi, Theta, Root e.t.c. (you can find it in the smilies pop up window, and it used to be on Ally's sig.. not too sure whether it's still there lol.) But yeah, it makes the question much easier to read and get accross. Cheers.