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Hey guys, this is my second posts here, last week was my first week of uni. I've done most of my Phys homework but I'm stuck with the last 3 questions

1.Given three points A,B and C which have coordinates (1,2,3); (2,-1,5); (-3,4,1). Find the area of triangle which has these three pints at its corners.

What I've tried is I drew these three points on a X,Y,Z plane and work out the area by finding the surface area by drawing each in 2D X,Y , X,Z and Y,Z. But that didn't seem to work.:tongue2:

2.The three vectors shown below, have magnitudes a=3.00, b=4.00 and c=10.0. a) Calculate the x and y components of these vectors. b) Find the numbers p and q such that c= pa + qb.

I have been doing research on google and Wiki for probably three hrs and i stil don't know anything about it.(I'm sorry, pls help, I'm just too dumb for it.:uhh: )

3.Show that, the vectors A = 3i + (-2j) + k, B = i - 3j + 5k and C = 2i + j - 4k can form the rectangular triangle.

Like, I want to know what to do first and what formulas to use to solve these questions. I got absolutely no ideas how to handle these question, from highschool I have learnt nothing about 3D coordinates things, only 2D..

Thanks a lot guys.

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# Homework Help: About a triangle

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