Area of Parallelogram

**Del** · April 21st 2008, 10:52 AM

Find the area of the parallelogram with vertices at

and

Area = ?

I've found the base vector multiplied by the sidw vector to be

, or 50.1996. I need to find the angle between these two vectors.

**TheEmptySet** · April 21st 2008, 11:58 AM

Originally Posted by Del

Find the area of the parallelogram with vertices at

and

Area = ?

I've found the base vector multiplied by the sidw vector to be

, or 50.1996. I need to find the angle between these two vectors.

to find the angle between two vectors use the dot product

$v_1=3 \vec i -5 \vec j,v_2=-3 \vec i -11\vec j$

$v_1 \cdot v_2=|v_1||v_2|\cos(\theta)$

$-9+55=\sqrt{34} \cdot \sqrt{130} \cos(\theta)$

$\cos(\theta)=\frac{46}{\sqrt{4420}}$

Check my work as this was done while I was riding a bus without a calculator, but the theory is correct.

good luck.