Question

PLEASE HELP! Will give medal!! Classify the triangle with vertices (0, 8) , (7, -2), and(-7, -2).

right scalene

obtuse scalene

acute isosceles

right isosceles
(if you can please explain because I don't understand :( )

Answer 1

@kirbykirby

Answer 2

Is this on a graph

Answer 3

and what next @kirbykirby

Answer 4

Can you at least identify if it's scalene or isosceles?

Answer 5

isosceles

Answer 6

yes :) so we are down to 2 choices. acute or right isosceles, so it's a matter of identifying if all the angles are acute, or if one of them forms a right angle

Answer 7

so?

Answer 8

Well to be exact, one way you could determine the angles is to use the Cosine Law. Or, another way is to identify that you have 2 right-angled triangles (the y-axis cuts down the middle of the triangle forming two right-angled triangles) and then you can use basic trigonometry to figure out the angles. Although... if you have an exact graph of the triangle (using quad paper, or some software), you could just "eye-ball" it I suppose if all the angles look obviously acute.

But.. really since you have an isosceles triangle, the only angle that you actually only need to check the the one at the vertex (0, 8) since the equal angles of an isoceles triangle are always less than 90 degrees.