Posted by **y912f** on Friday, January 16, 2009 at 8:39pm.

a question just like this one was on one of my homeworks..i asked for help but i didnt understand the explanation..so i had to gues..nd now i have that kind of quesion again on my homework. pleease explain this thoroughly

find the value of s in the interval [0,pi/2] that makes the statement true

1. tan s= 6.86874202

thnks to whoever answers adn explains it:)

- trigonometry -
**Reiny**, Friday, January 16, 2009 at 8:57pm
you are told that

tan s = + 6.86874..

so by the CAST rule, the angle must be in the I or III quadrant.

but our domain is from 0 to pi/2 which is only quadrants I and II.

and since they are using radians to describe the domain, we should also answer in radians.

set your calculator to radians,

enter

inv tan or 2nd function tan

6.68742..

=

I got s = 1.42622 radians

- trigonometry -
**y912f**, Friday, January 16, 2009 at 9:02pm
ya see this somehow doesnt work on my calculator

[pi,3pi/2];tan s=1

so you have to enter inv tan 1??

confuusedd

- trigonometry -
**Reiny**, Friday, January 16, 2009 at 9:20pm
let's try it with degrees first

set you calc to degrees

test #1

enter

tan

45

=

you should get 1

now work it backwards (the inverse)

at the top left you should have either an "INV" key or 2ndF key

enter:

2ndF

tan

1

=

you should get 45 degrees

If that doesn't work it could be that on your calc you have to enter the number first.

let me know if it worked.

If it worked, set your machine to radians and repeat the steps in the same way as noted above.

- trigonometry -
**y912f**, Saturday, January 17, 2009 at 1:56pm
when i do tan 45 i get 1.6197..

do you know any site where i can use a calculator...

- trigonometry -
**Damon**, Saturday, January 17, 2009 at 2:12pm
http://www.mathsisfun.com/scientific-calculator.html

- trigonometry -
**y912f**, Saturday, January 17, 2009 at 2:25pm
thnks:)

- trigonometry -
**Reiny**, Saturday, January 17, 2009 at 4:12pm
y912f, you have your calculator set to radians

yes, tan 45 radians = 1.6197

look for a key that says DRG, it will toggle your setting beteen degrees, radians and gradians

- trigonometry -
**y912f**, Saturday, January 17, 2009 at 4:47pm
ya Damon already helped me understand the problem

i set it to radians. entered 1, atan and it equaled .785

then entered +, pi= 3.926radians

in other words 5pi/4

thanks for all your help tooo!!!!

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