Answer:
8.6
Step-by-step explanation:
60.2/7 =8.6
Step-by-step explanation:
Let x represent theta.

Using the angle addition trig formula,



Multiply one side at a time
Replace theta with x , the answer is

2. Convert 30 degrees into radian

Using tangent formula,


Tan if pi/6 is sqr root of 3/3

Since my phone about to die if you later simplify that,
you'll get

Replace theta with X.
For this case we have an equation of the form:
y = A * (b) ^ t
Where,
A: initial amount
b: decrease rate
t: time in years.
Substituting values we have:
7 = A * (0.5) ^ ((1/20) * t)
For t = 45 years we have:
7 = A * (0.5) ^ ((1/20) * 45)
Clearing A:
A = 7 / ((0.5) ^ ((1/20) * 45))
A = 33.3
Answer:
the density of the substance when it was deposited 45 years ago was:
A = 33.3 milligrams per square centimeter
2.2 - 2.5 - 3.4
-3.7
.................