Coordinate Geometry help

It's question 6, can anyone help me?

I got 6ai) 3/2 ii) (0,7/2) b) I got 2x+3y-17

It's mainly the part c but you need some of that info for this question, so I got A(0. 7/2) B(1,5) and C(17/2, 0) and tried to use the distance formula, is this the correct method? I got AB = sqrt(2) which seems reasonable but then BC = sqrt(125 so sqrt(250) as the final area, this seems so wrong though? Thanks!

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you use distance formula indeed

I got the area as 65/4

Method is fine. Distances may need checking though.

I dont know what I'm doing wrong, have I used the wrong coordinates?;(

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I used A, B and C and found AB and AC
what have you got for these?

I haven't worked it out fully but, at a glance, your distance for AB alone is wrong.
Are you using $\sqrt {(x_1-x_2)^2+(y_1-y_2)^2}$ ?

Yeah I'm using that formula and I got sqrt(2) for AB and AC I got sqrt(125)?

what coordinates do you have for A, B and C?

A(0,7/2) B(1,5) and C(17/2,0) :s

I got the same.

from these I got AB=√(13/4)=(1/2)√13 and BC = √(325/4)=(5/2√13)

Got it, thanks!
Then do I just need to multiply the two?

naturally

and should it give 65/4? :P

yes

Thanks!