# Evaluate Definite trig integral

• Sep 2nd 2011, 11:39 PM
celtic1234
Evaluate Definite trig integral
Hi all,
I have the following Question and my answer is not tying up with the answer given in the text book-it's probably me but this book has been wrong a few times already.
So that i do not waste anymore time can somebody tell me whether it's me or not?

Evaluate Integration sign(cos x.dx) between (pi/4) and 0.

Sorry must look at how to use tex...

The integral of cos x is sin x, and sin(pi/4)-sin(0)=0.0137

The book gives 0.707?

Help appreciated
John
• Sep 3rd 2011, 12:00 AM
alexmahone
Re: Evaluate Definite trig integral
Quote:

Originally Posted by celtic1234
Hi all,
I have the following Question and my answer is not tying up with the answer given in the text book-it's probably me but this book has been wrong a few times already.
So that i do not waste anymore time can somebody tell me whether it's me or not?

Evaluate Integration sign(cos x.dx) between (pi/4) and 0.

Sorry must look at how to use tex...

The integral of cos x is sin x, and sin(pi/4)-sin(0)=0.0137

The book gives 0.707?

Help appreciated
John

You need to change your calculator's mode from degrees to radians.
• Sep 3rd 2011, 12:09 AM
celtic1234
Re: Evaluate Definite trig integral
thank you-feeling silly!
• Sep 3rd 2011, 02:20 AM
e^(i*pi)
Re: Evaluate Definite trig integral
Also $\displaystyle 0.707 \approx \dfrac{\sqrt2}{2}$