Answer:

Step-by-step explanation:
We will use the co-function identity for sine, where:

Since sin(21)=0.358=cos(x). This means that:

Solve for x. Add x to both sides:

Subtract 21 from both sides:

Hence:

Answer:
a) 16.82 mg
b) 24 days
Step-by-step explanation:
Formula for exponential growth is given as:

Where A is the final population
is the initial population
b is the growth factor
c is the time taken for the growth 'b'
t is the amount of time
Here, We are given the following:
= 5 mg
b = 2 (Given because it doubles)
c = 4 days
a) A = ?
Using the formula:

b) Given
A = 320 mg
t = ?
Using the above formula again:

So, the answers are:
a) 16.82 mg
b) 24 days
If the points are
collinear, then that would mean that the points lie on the same line when joined
to each other. In order to confirm this, the distances between the points must
sum up to the length of the line.<span>
AB + BC = AC
7 + 4 ? 9
11 ≠ 9
<span>Since they do not sum up, therefore, the points are not
collinear.</span></span>