10=1+9 1x9=9
=2+8 2x8=16
=3+7 3x7=21
=4+6 4x6=24
=5+5 5x5=25
↑ Left: the possible measurements of the two fences, Right: the possible areas

out of the areas calculated, 25 sq feet is the maximum. :)

Ans: 25 square feet

5 0

2 years ago

Find the length of the arc of the circular helix with vector equation r(t) = 2 cos t i + 2 sin t j + tk from the point (2, 0, 0)

USPshnik [31]

$\vec r(t)=2\cos t\,\vec\imath+2\sin t\,\vec\jmath+t\,\vec k$

$\implies\vec r'(t)=-2\sin t\,\vec\imath+2\cos t\,\vec\jmath+\vec k$

$\implies\|\vec r'(t)\|=\sqrt{(-2\sin t)^2+(2\cos t)^2+1^2}=\sqrt5$

Then the length of the arc is

$\displaystyle\int_0^{2\pi}\|\vec r'(t)\|\,\mathrm dt=\sqrt5\int_0^{2\pi}\mathrm dt=2\sqrt5\,\pi$

4 0

3 years ago

yulyashka [42]

The answer is C because it like adding 11.40+00.40 and that would be 12:20

3 0

2 years ago