## katherinekc Group Title Find the angle between the given vectors to the nearest tenth of a degree. u = <8, 7>, v = <9, 7> one year ago one year ago

1. ZeHanz Group Title

You could use the formula:$\cos \theta=\frac{ \vec u \cdot \vec v}{ |\vec u||\vec v| }$assuming you are familiar with the dot product of vectors.

2. Sshmoo Group Title

here it is on mathematica.

3. katherinekc Group Title

that wouldnt let me open it @Sshmoo

4. katherinekc Group Title

im just learning it so im still so comfused

5. Sshmoo Group Title

i'll try converting it to a different file, all it is is a graph of the vectors and a dot product. It just looks shinier.

6. katherinekc Group Title

ohok

7. Sshmoo Group Title

here it is in PDF

8. katherinekc Group Title

okk hm so

9. katherinekc Group Title

so which of these would the answer be ? -8.3° 1.7° 3.3° 13.3°

10. ZeHanz Group Title

If you calculate cos theta, you get: $\cos \theta=\frac{ 8 \cdot 9 + 7 \cdot 7 }{ \sqrt{8^2+7^2}\sqrt{9^2+7^2} }=\frac{ 72+49 }{\sqrt{113}\sqrt{130} }=\frac{ 121 }{ \sqrt{113} \sqrt{130}}\approx 0.99833$Now take the inverse cosine (cos^-1 on your calculator) to see the answer.

11. katherinekc Group Title

THANK YOU!

12. ZeHanz Group Title

yw!