Please help on geometry  analytic geometry
posted by Knights .
What is the area, in square units, of a triangle whose vertices are at (4,1), (10,3) and (4,5) ?
How to do this?

It helps if you plot the points first, then you can find the length of the sides of the triangle.
area of a triangle is
1/2 base times height. 
http://www.algebra.com/algebra/homework/Triangles/Triangles.faq.question.461705.html

ok thanks

I could also i think find the area of the square/rectangle and minus the pieces that are not part of the triangle

Knights, If you are in analytic geometry, I am pretty certain your teacher expects an analytical approach, not a graphical approach. See the example I posted.