<u>Answer:</u>
<u>Step-by-step explanation:</u>
Equation of parabola with focus at (0,-4) and directrix is 
.
We know that parabola is the locus of all the points such that the distance from fixed point on the parabola to fixed line directrix is the same.
The parabola is opening downwards.
Let any point on parabola is (x,y).
Distance from focus(0,-4) to (x,y) = 
Look at the picture.
We know, the sum of the measures of the triangle is equal 180°.
Therefore in ΔBCD we have:
<em>subtract 137 from both sides</em>
Answer: x° = 90°, y° = 43°.
Answer:
socratic is a good app for math answers
Step-by-step explanation:
or faster help then this
Answer:
In basic terms, a population is the total number of individuals, animals, items, observation, data, etc. So the sample, in other words, is a portion, part, or fraction of the whole group, and acts as a subset of the population. Samples are used in a variety of settings where research is conducted.
The decay formula is
N(t) = N₀ exp(-kt)
where
N₀ = 45 g, original mass
N(t) = mass after time t, days
k = 0.1109, the decay constant.
At half life, N(t) = (1/2)*N₀. Therefore
1/2 = exp(-0.1109t)
Take natural log of each side.
ln(0.5) = -0.1109t
t = ln(0.5)/(-0.1109) = 6.25 days
Answer: 6.3 days (nearest tenth)
