Answer:
[tex]r'(t)=(sin(6t)+6tcos(6t),2t,cos(7t)-7tsin(7t))[/tex]
Step-by-step explanation:
We need to find the derivative [tex]r'(t)[/tex] of the vector function :
[tex]r(t)=(tsin(6t),t^{2},tcos(7t))[/tex]
In order to find [tex]r'(t)[/tex], we are going to differentiate each of its components ⇒
We can write the following ⇒
[tex]r(t)=(f(t),g(t),h(t))=(tsin(6t),t^{2},tcos(7t))[/tex] ⇒
[tex]f(t)=tsin(6t)\\g(t)=t^{2}\\h(t)=tcos(7t)[/tex]
Let's differentiate each function to obtain [tex]r'(t)[/tex] :
[tex]f(t)=tsin(6t)[/tex] ⇒ [tex]f'(t)=1.sin(6t)+t.cos(6t).6=sin(6t)+6tcos(6t)[/tex] ⇒
[tex]f'(t)=sin(6t)+6tcos(6t)[/tex]
Now with [tex]g(t)[/tex] :
[tex]g(t)=t^{2}[/tex] ⇒
[tex]g'(t)=2t[/tex]
With [tex]h(t)[/tex] :
[tex]h(t)=tcos(7t)[/tex] ⇒ [tex]h'(t)=1.cos(7t)+t[-sin(7t)].7[/tex] ⇒
[tex]h'(t)=cos(7t)-7tsin(7t)[/tex]
Finally we need to complete [tex]r'(t)=(f'(t),g'(t),h'(t))[/tex] with its components :
[tex]r'(t)=(sin(6t)+6tcos(6t),2t,cos(7t)-7tsin(7t))[/tex]