Answer:
r = 144 units
Step-by-step explanation:
The given curve corresponds to a parametric function in which the Cartesian coordinates are written in terms of a parameter "t". In that sense, any change in x can also change in y owing to this direct relationship with "t". To find the length of the curve is useful the following expression;

In agreement with the given data from the exercise, the length of the curve is found in between two points, namely 0 < t < 16. In that case a=0 and b=16. The concept of the integral involves the sum of different areas at between the interval points, although this technique is powerful, it would be more convenient to use the integral notation written above.
Substituting the terms of the equation and the derivative of r´, as follows,

Doing the operations inside of the brackets the derivatives are:
1 ) 
2) 
Entering these values of the integral is

It is possible to factorize the quadratic function and the integral can reduced as,

Thus, evaluate from 0 to 16
The value is 
Robin has to go shopping for her brother's birthday.
She already bought "x" presents for him.
The next day, Robin bought "2" more presents for him just in time for his birthday.
When she got home and celebrated his birthday, her beother opened, in total, "9" presents.
--- What is the number of presents that Robin had originally purchased? ---
Answer:
yes i think
Step-by-step explanation:
9.81 times 10 to the -5th power
Idk...................................