coordinate geometry (1 Viewer)

[kaha167]

hey everyone,
im doing revision for my trials which are coming up in the coming weeks,
i was given a revision sheet and am unsure of how to do the following:
Given points A (-2,5), B (10,-1), and C (5,9) find teh area of triangle ABC.
How do i do this?
I cant find any resources of ever doing this exercise,
any help is greatly appreciated,
Cheers.

 

[SeCKSiiMiNh]

just find the length of each side and use your trig rule to find the area.

 

[ohexploitable]

Find two lengths, an included angle then use the area of a triangle formula.

 

[hscishard]

Since it's a 2 unit topic...

Sketch
Find the length of one side. Then find the length perpendicular to the opposite point.

Use Area of triangle. 1/2AB

 

[ohexploitable]

Since it's a 2 unit topic...

Sketch
Find the length of one side. Then find the length perpendicular to the opposite point.

Use Area of triangle. 1/2AB

There's no 1/2ab sinC in 2 unit? I done that in year 10...

 

[hscishard]

How would you find an angle? It's not given.
You needa do 3 unit trig.

Unless.. He would have to find all 3 sides, use the cosine rule to find an angle and then use 1/2ab sin(c)

 

[ohexploitable]

How would you find an angle? It's not given.
You needa do 3 unit trig.

Unless.. He would have to find all 3 sides, use the cosine rule to find an angle and then use 1/2ab sin(c)

Isn't that 2 unit?

 

[SeCKSiiMiNh]

Isn't that 2 unit?

nope. 3 unit.

 

[annabackwards]

nope. 3 unit.

Yep. Tis at the very beginning of 3U.

Anywho, you could find the length of one side. Then find the equation of that side and use the perpendicular distance formula to find the distance between that side and the opposite vertex

If i were you, i'd check that the triangle isn't a right angled triangle before using the method above though XD