I believe it’s AB AND DF, ZBAC = ZDEF
Answer:
Step-by-step explanation:
eq. of directrix is y-1=0
let (x,y) be any point the parabola.
then\sqrt{ (x-6)^2+(y-2)^2}=\frac{y-1}{(-1)*2}
squaring
x²-12x+36+y²-4y+4=y²-2y+1
x²-12 x+40-1=4y-2y
2y=x²-12x+39=x²-12x+36+3
(x-6)²=2y-3
The answer is 28 years
At = A0 * e^(-k * t)
At = 12 g
A0 = 15 g
k = 7.9 × 10^-3 = 0.0079
t = ?
12 = 15 * e^(-0.0079 * t)
12/15 = e^(-0.0079 * t)
0.8 = e^(-0.0079 * t)
Logarithm both sides (because ln(e) = 1:
ln(0.8) = ln(e^(-0.0079 * t))
ln(0.8) = (-0.0079 * t) * ln(e)
-0.223 = -0.0079 * t
t = -0.223 / -0.0079
t = 28.23
t ≈ 28 years
