# sin and cos 45 degress

• April 13th 2012, 08:34 AM
davellew69
sin and cos 45 degress
ok the book quotes sin and cos of 45 degress as 1/sqrt 2, but my calculator give the answer of 2/sqrt 2
Im convinced the book is wrong , or am I nuts?
• April 13th 2012, 08:45 AM
Prove It
Re: sin and cos 45 degress
Quote:

Originally Posted by davellew69
ok the book quotes sin and cos of 45 degress as 1/sqrt 2, but my calculator give the answer of 2/sqrt 2
Im convinced the book is wrong , or am I nuts?

Both answers are correct as the two expressions are equivalent.

\displaystyle \begin{align*} \frac{1}{\sqrt{2}} = \frac{1 \cdot \sqrt{2}}{\sqrt{2}\cdot\sqrt{2}} = \frac{\sqrt{2}}{2} \end{align*}
• April 13th 2012, 11:19 AM
davellew69
Re: sin and cos 45 degress
thanks, I thought I was going nuts
• April 14th 2012, 01:39 PM
HallsofIvy
Re: sin and cos 45 degress
Did it ever occur to you to evaluate both 1/sqrt(2) and sqrt(2)/2 on your calculator?