# Math Help - sin and cos 45 degress

1. ## 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?

2. ## Re: sin and cos 45 degress

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*}

3. ## Re: sin and cos 45 degress

thanks, I thought I was going nuts

4. ## 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?