Answer:
θ ≈ 71.6°
Step-by-step explanation:
The angle between two lines with slopes m₁ and m₂ is:
tan θ = | (m₂ − m₁) / (1 + m₁m₂) |
Here, m₁ = -2 and m₂ = 1.
tan θ = | (1 − (-2)) / (1 + (-2)(1)) |
tan θ = | 3 / -1 |
tan θ = 3
θ ≈ 71.6°
Applying a dilation centered at the origin with scale factor
has the effect of multiplying both coordinates of a point by
:

So, in your case, the coordinates of the points double:

Answer:
That sucks.
Step-by-step explanation:
Multiply the equation:

The solution set is the same, because multiplying both sides of an equation by a non-zero number doesn't change the solution set. In fact, if you rewrite the equation as

Multiplying this by 3 (or whatever number, for all it matters) gives

Now, a product is zero if and only if at least one of the factor is zero. So, either
or 
Since the first is clearly impossible, the second one must be true, which is the original equation.
I think you can draw two of them.
As you walk around the triangle in the clockwise direction,
you can run into the sides in the order of
3 ==> 4 ==> 1
or in the order of
3 ==> 1 ==> 4 .
Those are mirror images of each other. So they're not congruent,
and I think they're considered different triangles.