# Math Help - using TI-83 to sovle angle between two vectors question...

1. ## using TI-83 to sovle angle between two vectors question...

So I'm following along in my book where it comes to put the final values in the equation:

cosO=u*v/|u|*|v|

= -1/sqrt 6 (5)

and I should get -0.14 But I'm not getting it?

am I inputting it into the calculator the wrong way?

I use cos^-1(-1/sqrt 6 (5)) but I get 1.85 and not -0.14

2. ## Re: using TI-83 to sovle angle between two vectors question...

Originally Posted by sara213
So I'm following along in my book where it comes to put the final values in the equation:

cosO=u*v/(|u|*|v|) <--- nearly correct

= -1/sqrt 6 (5)

and I should get -0.14 But I'm not getting it?

am I inputting it into the calculator the wrong way?

I use cos^-1(-1/sqrt 6 (5)) but I get 1.85 and not -0.14
1. I don't understand this term: -1/sqrt 6 (5)

Do you mean
-1/(sqrt(6)* (5)) .....or: -1/(sqrt(6)) * (5) .....or: (-1/(sqrt(6)) * (5) .....or: -1/sqrt((6)* (5))
$-\frac1{\sqrt{6} \cdot 5}$ ................or: $-\frac1{\sqrt{6}} \cdot 5$ .................................................. .or: $-\frac1{\sqrt{6 \cdot 5}}$