Answer:
The substance half-life is of 4.98 days.
Step-by-step explanation:
Equation for an amount of a decaying substance:
The equation for the amount of a substance that decay exponentially has the following format:

In which k is the decay rate, as a decimal.
k-value of 0.1392.
This means that:

Find the substance's half life, in days.
This is t for which
. So







The substance half-life is of 4.98 days.
Answer:
2/3
Step-by-step explanation:
42/63 = 2/3
15/22.5 = 2/3
Answer: 
Step-by-step explanation:
For this exercise you need to use the Inverse Trigonometric function arcsine, which is defined as the inverse function of the sine.
Then, to find an angle α, this is:

In this case, you can identify that:

Then, substituting values into
and evaluating, you get that the measure of the angle "C" to the nearest degree, is:

C. three sides with the same length