Question

What type of triangle is formed by joining the points`D(7, 3), E(8, 1),` and `F(4, -1)`?

Answer 1

It’s a right angle triangle.

Explanation:

`DE^2 = (7-8)^2+(3-1)^2 = 5`

`EF^2 = ((8-4)^2+(1-(-))^2)= 20`

`DF^2 = ((7-4)^2+(3-(-1)^2 = 25`

Three sides are `sqrt5, 2sqrt5, 5`

As `DE^2 + EF^2 = DF^2`, `(5+20 = 25)`,

its a right angle triangle.