Chapter 4: Problem 15
A ship sails north for 2 miles and then west for 5 miles. How far is the ship from its starting point?
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Chapter 4: Problem 15
A ship sails north for 2 miles and then west for 5 miles. How far is the ship from its starting point?
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Suppose a country's population increases by a total of \(6 \%\) over a three- year period. What is the continuous growth rate for this country?
The functions cosh and \(\sinh\) are defined by $$ \cosh x=\frac{e^{x}+e^{-x}}{2} \text { and } \sinh x=\frac{e^{x}-e^{-x}}{2} $$ for every real number \(x .\) For reasons that do not concern us here, these functions are called the hyperbolic cosine and hyperbolic sine; they are useful in engineering. Show that cosh is an even function.
Suppose \(\left(x_{1}, y_{1}\right)\) and \(\left(x_{2}, y_{2}\right)\) are the endpoints of a line segment. (a) Show that the line containing the point \(\left(\frac{x_{1}+x_{2}}{2}, \frac{y_{1}+y_{2}}{2}\right)\) and the endpoint \(\left(x_{1}, y_{1}\right)\) has slope \(\frac{y_{2}-y_{1}}{x_{2}-x_{1}}\). (b) Show that the line containing the point \(\left(\frac{x_{1}+x_{2}}{2}, \frac{y_{1}+y_{2}}{2}\right)\) and the endpoint \(\left(x_{2}, y_{2}\right)\) has slope \(\frac{y_{2}-y_{1}}{x_{2}-x_{1}}\). (c) Explain why parts (a) and (b) of this problem imply that the point \(\left(\frac{x_{1}+x_{2}}{2}, \frac{y_{1}+y_{2}}{2}\right)\) lies on the line containing the endpoints \(\left(x_{1}, y_{1}\right)\) and \(\left(x_{2}, y_{2}\right)\)
Suppose a colony of bacteria has a continuous growth rate of \(15 \%\) per hour. By what percent will the colony have grown after eight hours?
(a) Using a calculator, verify that $$ \log (1+t) \approx 0.434294 t $$ for some small numbers \(t\) (for example, try \(t=0.001\) and then smaller values of \(t\) ). (b) Explain why the approximation above follows from the approximation \(\ln (1+t) \approx t\)
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