Answer:
Step-by-step explanation:
Any point on a given parabola is equidistant from focus and directrix.
Given:
Focus of the parabola is at 
.
Directrix of the parabola is 
.
Let 
be any point on the parabola. Then, from the definition of a parabola,
Distance of from focus = Distance of from directrix.
Therefore,
Squaring both sides, we get
![(x-2)^{2}+(y-8)^{2}=(y-10)^{2}\\(x-2)^{2}=(y-10)^{2}-(y-8)^{2}\\(x-2)^{2}=(y-10+y-8)(y-10-(y-8))...............[\because a^{2}-b^{2}=(a+b)(a-b)]\\(x-2)^{2}=(2y-18)(y-10-y+8)\\(x-2)^{2}=2(y-9)(-2)\\(x-2)^{2}=-4(y-9)\\y-9=-\frac{1}{4}(x-2)^{2}\\y=-\frac{1}{4}(x-2)^{2}+9](https://tex.z-dn.net/?f=%28x-2%29%5E%7B2%7D%2B%28y-8%29%5E%7B2%7D%3D%28y-10%29%5E%7B2%7D%5C%5C%28x-2%29%5E%7B2%7D%3D%28y-10%29%5E%7B2%7D-%28y-8%29%5E%7B2%7D%5C%5C%28x-2%29%5E%7B2%7D%3D%28y-10%2By-8%29%28y-10-%28y-8%29%29...............%5B%5Cbecause%20a%5E%7B2%7D-b%5E%7B2%7D%3D%28a%2Bb%29%28a-b%29%5D%5C%5C%28x-2%29%5E%7B2%7D%3D%282y-18%29%28y-10-y%2B8%29%5C%5C%28x-2%29%5E%7B2%7D%3D2%28y-9%29%28-2%29%5C%5C%28x-2%29%5E%7B2%7D%3D-4%28y-9%29%5C%5Cy-9%3D-%5Cfrac%7B1%7D%7B4%7D%28x-2%29%5E%7B2%7D%5C%5Cy%3D-%5Cfrac%7B1%7D%7B4%7D%28x-2%29%5E%7B2%7D%2B9)
Hence, the equation of the parabola is .
For 6 plug in each of the answers for x and see if the product =3.2
Answer for 6: A
For 7 you turn the percentage into a decimal and multiply that by the number in which you know and you find the answer.
Answer for 7: D
30% of 42 is 12.6$.
42-12.6 = 29.4$ is the price of the pair with discount applied.
Tax 7%
29.4 * 7% = 2.06
29.4$ + 2.06$ = 31.46 $ final price with discount and tax applied.
Remark
I think you want us to do both 3 and 4
Three
QR is 4 points going left from the y axis + 2 points going right from the y axis.
QR = 6 units long.
RT is 4 units above the x axis and 3 units below the x axis
RT = 7 units long
TS = 3 units. For this one you just go from T to S. The graph really helps you. You just need to count.
Problem 4
You need to find the area of the combined figure. You could do it as a trapezoid, which might be the easiest way. I'll do that first.
Area = (b1 + b2)*h/2
Givens
B1 = QR = 6
B2 = UT + TS = 6 + 3 = 9
h = RT = 7
Area
Area = (6 + 9)*7/2
Area = 15 * 7 / 2
Area = 52.5
Comment
You could break this up into a rectangle + a triangle
Find the area of QRTU and add the Area of triangle RTS
<em>Area of the rectangle </em>= L * W
L = RT = 7
W = QR = 6
Area = 7 *6 = 42
<em>Area of the triangle</em> = 1/2 * B * H
B = TS = 3
H = RT =7
Area = 1/2 * 3 * 7
Area = 1/2 * 21
Area = 10.5
Total Area = 42 + 10.5 = 52.5 Both answers agree.
