Answer:
15
-----
32
Step-by-step explanation:
3 5 15
-- * -- == ---
4 8 32
The straight edge of the semicircle is 4 units, as this is this the diameter.
The circumference of the full circle is
C = pi*d = pi*4 = 4pi
which is the distance around the full circle (aka circle's perimeter)
So half of this is 4pi/2 = 2pi
Add this onto the straight edge length to get 4+2pi as the exact distance around the entire semicircle. This includes both straight and curved portions.
If you use the approximation pi = 3.14, then 4+2*pi = 4+2*3.14 = 10.28 is the approximate answer. To get a more accurate answer, use more decimal digits in pi.
---------------------------------------------------------
In summary,
exact answer in terms of pi is 4+2pi units
approximate answer is roughly 10.28 units (using pi = 3.14)
Answer:
Step-by-step explanation:
Let x be the original price.
( 1 - 20% ) x = 23.2
The amount of the substance (At) at any time t is calculated through the equation,
At = (A0)(e^-kt)
where A0 is the initial amount and k is constant.
For the half-life,
ln (At / A0) = ln 0.5 = -k(5270 years)
The value of k is 1.3153x10^-4 / year.
Substituting this value to the same equation, where At = 0.25A0
ln 0.25 = -(1.3153 x 10^-4)(t)
The value of t from this equation is 10540 years. The closest value to this is letter A.
