# Area of triangle using cross product

• May 4th 2008, 08:37 AM
paushali
Area of triangle using cross product
Find the area of the triangle if the vertices are:
A=(2,1)
B=(4,-1)
C=(6,3) using vector cross product.
• May 4th 2008, 08:47 AM
galactus
$P_{1}(2,1), \;\ P_{2}(4,-1), \;\ P_{3}(6,3)$

$\overrightarrow{P_{1}P_{2}}=(2,-2)$

$\overrightarrow{P_{1}P_{3}}=(4,2)$

$\overrightarrow{P_{1}P_{2}}\times\overrightarrow{P _{1}P_{3}}=(0,0,12)$

$\frac{1}{2}||\overrightarrow{P_{1}P_{2}}\times\ove rrightarrow{P_{1}P_{3}}||=?$

Can you finish?.