we are given

we can find x , y and z

now, we can use arc length formula

now, we can find derivative

now, we can plug values
and we get



...........Answer
Answer: C
Step-by-step explanation:
On the big triangle, the length from the origin to point A is three blocks. On the new triangle it is only one block. And it is getting smaller, so it is a fraction.
1/3 over the y axis.
Answer:
We can use the sample about 42 days.
Step-by-step explanation:
Decay Equation:



Integrating both sides


When t=0, N=
= initial amount




.......(1)
.........(2)
Logarithm:
130 days is the half-life of the given radioactive element.
For half life,
,
days.
we plug all values in equation (1)






We need to find the time when the sample remains 80% of its original.







We can use the sample about 42 days.
90/15-7/15=83/15 the correct answer to this equation.