Answer:
I'm pretty sure A but let me know if I'm wrong
If this is the dance position you are describing, then the arm and the leg of the dancer both make "right" angles (90º angles) to the floor.
Answers:
a. Given
b. Transitive property of congruence
c. Vertical angles are congruent
d. Transitive property of congruence
Let me know if you need any clarification as to how I got those answers. They should be self-explanatory but I'm happy to clarify further if needed.
I have the best ans and that is
Vertex<em> </em>is at 
<em>y-intercept</em> is 3.
The parabola <em>opens up</em>.
Step-by-step explanation:
The graph of the equation is hereby attached in the answer area.
Vertex is the point on the parabola where the graph crosses its axis of symmetry. The axis of symmetry here(
), is shown with the dotted line in the graph attached.
<em>y-intercept </em>is defined as the value of y where the graph crosses the y-axis. In other words, when
. Putting
And, the graph opens up as shown the graph figure as well. It is also evident from the co-efficient of
in the given equation
. Here, co-efficient of
So, vertex<em> </em>is at 
<em>y-intercept</em> is 3.
The parabola <em>opens up</em>.