Thread: Trig Problem

The problem is:

cos(-7pi/12)





I used the half angle formula to get: -(sqrt(3)-1)*sqrt(2)/(4)


Somehow or another the computer system isn't taking my answer.

Thanks for the help!

Originally Posted by qbkr21

The problem is:

cos(-7pi/12)





I used the half angle formula to get: -(sqrt(3)-1)*sqrt(2)/(4)


Somehow or another the computer system isn't taking my answer.

Thanks for the help!

First drop the negative, cosine is an even function.


Next convert to degree if that is easier for thee,

Next you can express this angle as,

Now since,

That means,

This seems to be the same answer I got, and it still doesn't want to fit into the system...Is there another way you can express this?

Thanks!

Originally Posted by qbkr21

The problem is:

cos(-7pi/12)





I used the half angle formula to get: -(sqrt(3)-1)*sqrt(2)/(4)


Somehow or another the computer system isn't taking my answer.

Thanks for the help!

Originally Posted by ThePerfectHacker

First drop the negative, cosine is an even function.


Next convert to degree if that is easier for thee,

Next you can express this angle as,

Now since,

That means,

Originally Posted by qbkr21

This seems to be the same answer I got, and it still doesn't want to fit into the system...Is there another way you can express this?

Thanks!

Unless you changed your original answer you had:


ThePerfectHacker had:


So the answers are not the same.

-Dan

Here are the directions the computer system is still not taking it:

Use a sum or difference formula or a half angle formula to determine the value of the trigonometric functions. Give exact answers. Do not use decimal numbers. The answer should be a fraction or an arithmetic expression. If the answer involves a square root it should be enter as sqrt; e.g. the square root of 2 should be written as sqrt(2);



Thanks!

Originally Posted by qbkr21

Here are the directions the computer system is still not taking it:

Use a sum or difference formula or a half angle formula to determine the value of the trigonometric functions. Give exact answers. Do not use decimal numbers. The answer should be a fraction or an arithmetic expression. If the answer involves a square root it should be enter as sqrt; e.g. the square root of 2 should be written as sqrt(2);



Thanks!

You should enter:
sqrt(2 - sqrt(3))/2

or

(sqrt(2 - sqrt(3)))/2

The first one should do the trick, the second is being extra careful.

-Dan

Originally Posted by qbkr21

Here are the directions the computer system is still not taking it:

Use a sum or difference formula or a half angle formula to determine the value of the trigonometric functions. Give exact answers. Do not use decimal numbers. The answer should be a fraction or an arithmetic expression. If the answer involves a square root it should be enter as sqrt; e.g. the square root of 2 should be written as sqrt(2);



Thanks!

Read what ImPerfectHacker wrote carefully.

He did not say that:



what he did say was:



and that:



so:



RonL

Ok thanks Captain Black