# how to find f(x)=2x-tanx pls help

• February 19th 2011, 11:38 PM
how to find f(x)=2x-tanx pls help
I really dont know where to post this but i just want to find how to get this:
given: x=1

f(x)=2x-tanx

the answer is supposed to be 0.443.

Now my problem is how did he get 0.433 because i keep doing 2(1)-tan(1) and im getting 1.982544935 HELP IM NOT GOOD AT MATH(Crying)
• February 19th 2011, 11:59 PM
Sudharaka
Quote:

I really dont know where to post this but i just want to find how to get this:
given: x=1

f(x)=2x-tanx

the answer is supposed to be 0.443.

Now my problem is how did he get 0.433 because i keep doing 2(1)-tan(1) and im getting 1.982544935 HELP IM NOT GOOD AT MATH(Crying)

You have to consider that x=1 radians to get the desired answer. You had taken x=1 degrees.
• February 20th 2011, 12:07 AM
im really sorry but how do you do this? im doing 2(pi/180)-tan(pi/180)=0.03496 which is wrong.
• February 20th 2011, 12:15 AM
Sudharaka
Quote:

im really sorry but how do you do this? im doing 2(pi/180)-tan(pi/180)=0.03496 which is wrong.

$x~degrees=\left(\frac{pi}{180}\right)x~ rad\longleftrightarrow{x~ rad}=\left(\frac{180}{\pi}\right)x~degrees$

Therefore, $1~rad=\left(\frac{180}{\pi}\right)~degrees$
• February 20th 2011, 02:31 AM
HallsofIvy
Quote: