Answer:
Step-by-step explanation:
Because of the nature of the information we are given, we have no choice but to use the equation

and solve for a.
We know by the info that the vertex is (0, 84). We also know that if the vertex is at the origin, and that the base is 42 feet wide, it spans 21 feet to the right of the origin and 21 feet to the left of the origin. That means that we have 2 coordinates from which we need to pick one for our x and y in the equation. I don't like negatives, so I am going to choose the coordinate (21, 0) as x and y. Because this parabola opens upside down, as archways of door openings do, our "a" value better come out algebraically as a negative. Let's see...From the vertex we have that h = 0 and k = 84. So filling in:
and simplifying a bit:
0 = 441a + 84 and
-84 = 441a so
Good, a is negative. Your equation is, then:

Answer:
487
Step-by-step explanation:
The answer is 487 because you must look one place to the right of the whole number for the rounding digit on the right side of the decimal point which is 0. Then you round down since the digit is not greater than 5.
.
Answer:
This case has NO solutions.
Step-by-step explanation:
Notice that you are in a case of an obtuse triangle (one of its angles is larger than 90 degrees), the side opposite to the obtuse triangle is shorter than the side adjacent to the angle, so no actual triangle can be formed.
This can be found by simply trying to apply the Law of Sines to solve for the value of angle "B" opposite to side "b":

As shown above, we get an impossible mathematical condition (also call an absurd), since the sine of an angle cannot give a value larger than 1 (one).
Therefore, there is no angle we can find to build a triangle with the given data.