1) The definition of a scalene triangle is that ALL sides are different.
Now, to prove a triangle is scalene, we need to show that all three sides output different values. Therefore, selections with only two sides certainly are insufficient. If we look at the last two choices, you can easily spot that the second to the last is correct answer by comparing the definition of a scalene triangle.
2) You will need to perform something similar to the previous questions, which is, find the distance between the three points, and see if they are all different => scalene; all the same => equilateral; or two of them are the same => isosceles.
The distance formula between two points (a, b) and (c,d) is given as:

Just for you to check your work, the distances between three points are:
sqrt(34), sqrt(17), sqrt(37), which results a scalene triangle.
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The second choice! I hope my math is right!
Given: <span>2x-y-3=0.
find </span>equation for the line perpendicular to the given line that goes through the given point:<span>
(2;-1)koord of direction vector (i`m not know how it is called at you, because i'm from russia)</span><span>
=> (x-0)/2=(y-4)/-1 (</span>canonical <span>equation)
=>x+2y-8=0(general </span><span>equation)
</span>
<span>further:
{x+2y-8=0
{2x-y-3 =0 => y=13/5 x=14/5
(14/5; 13/5) - koord point on line
</span>|dist|=sqrt( (14/5-0)^2 + (13/5-4)^2 ) = sqtr(7.72) = 2.78
Удачи!
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