Answer:
Anton's definition is not valid.
Step-by-step explanation:
We have been given that Anton defines an acute angle as an angle that is not obtuse. We are asked to find whether Anton's definition is valid or not.
We know that an angle is known as acute angle whose measure is greater than 0 and less than 90 degrees.
We also know that an angle is known as obtuse angle whose measure is greater than 90 degrees and less than 180 degrees.
We know that a right triangle is neither acute nor obtuse. Since Anton hasn't mentioned a right triangle to his definition, therefore, his definition is not valid.
A milllion probably like 1 million
Two thirds times four equals eight thirds or two and two thirds cups
From the half life equation, the remaining fraction 
where t = total time elapsed and T = Half life
Now, it is given that, 
And remaining fraction is
So, substituting these values in the above equation,
Taking log both sides,
Solving, we obtain that,
years
The standard deviation is defined as the square root of the variance:
