Answer:
their distance is increasing at the rate of 41.6 miles/hr
Step-by-step explanation:
Given the data in the question;
first we determine the distance travelled by the first boat in 10 min when the second boat was crossing its path;
⇒ ( 30/60 ) × 10 = 5 miles
so as illustrated in the diagram below;
y² = x² + ( x + 5 )²
2y[tex]\frac{dy}{dt}[/tex] = 2x[tex]\frac{dx}{dt}[/tex] + 2(x+5)[tex]\frac{dx}{dt}[/tex]
y[tex]\frac{dy}{dt}[/tex] = ( 2x + 5 ) ][tex]\frac{dx}{dt}[/tex]
[tex]\frac{dy}{dt}[/tex] = [( 2x + 5 )/y ][tex]\frac{dx}{dt}[/tex] ------ let this be equation 1
Now, given that, [tex]\frac{dx}{dt}[/tex] = 30 miles/hr, when x = 10
so
y = √( 10² + 15² ) = √325
so from equation 1
[tex]\frac{dy}{dt}[/tex] = [( 2x + 5 )/y ][tex]\frac{dx}{dt}[/tex]
we substitute
[tex]\frac{dy}{dt}[/tex] = [( 2(10) + 5 ) / √325 ]30
[tex]\frac{dy}{dt}[/tex] = [ 25 / √325 ] × 30
[tex]\frac{dy}{dt}[/tex] = 41.6 miles/hr
Therefore, their distance is increasing at the rate of 41.6 miles/hr
