Topscore Test 2 Question

[hova137]

---

Members don't see this ad.

This is number 14 on the QR section:

In a 2-d coordinate system, point A (3,-6), point B (1,1), and point C (7,6). Find the area of triangle ABC.

For the explanation they came up with a formula which I am not sure how they derived. Can anyone tell me how to solve this in a simpler way? I tried using the distance formula but didn't know how to calculate the height of the triangle. Thanks!

 

[hova137]

bump

 

[Ibracadabra]

This is number 14 on the QR section:

In a 2-d coordinate system, point A (3,-6), point B (1,1), and point C (7,6). Find the area of triangle ABC.

For the explanation they came up with a formula which I am not sure how they derived. Can anyone tell me how to solve this in a simpler way? I tried using the distance formula but didn't know how to calculate the height of the triangle. Thanks!

I believe that for that question it's easier to just know the formula...
or else you have to go through too much calculations..
http://www.teacherschoice.com.au/Maths_Library/Trigonometry/triangle_given_3_points.htm like this... or i guess you can get two line functions that go 90 degrees to each other (using that m1m2=-1) and then get the length of the base and one side... it's just too much work 😛
I don't think this is necessary for the QR section 😛

 

[UndergradGuy7]

Think you are mentioning Heron's formula

http://en.wikipedia.org/wiki/Heron's_formula

 

[hova137]

thanks for the help! hope the DAT doesn't have something obscene such as this on there...I think I have seen this formula once in my life...