Answer:
The Commutative Law of Addition.
Step-by-step explanation:
Basically, this law says we can swap numbers over and still get the same number when we add. This has demonstrated exactly that.
Hope this helped!
Answer:
The length of rope is 20.0 ft . Hence, <u>option (1) </u> is correct.
Step-by-step explanation:
In the figure below AB represents pole having height 10 ft and AC represents the rope that is from the top of pole to the ground. BC represent the ground distance from base of tower to the rope.
The rope and the ground form a 30 degree angle that is the angle between BC and AC is 30°.
In right angled triangle ABC with right angle at B.
Since we have to find the length of rope that is the value of side AC.
Using trigonometric ratios


Putting values,

We know, 

On solving we get,
AC= 20.0 ft
Thus, the length of rope is 20.0 ft
Hence, <u>option (1)</u> is correct.
The position function of a particle is given by:

The velocity function is the derivative of the position:

The particle will be at rest when the velocity is 0, thus we solve the equation:

The coefficients of this equation are: a = 2, b = -9, c = -18
Solve by using the formula:
![t=\frac{-b\pm\sqrt[]{b^2-4ac}}{2a}](https://tex.z-dn.net/?f=t%3D%5Cfrac%7B-b%5Cpm%5Csqrt%5B%5D%7Bb%5E2-4ac%7D%7D%7B2a%7D)
Substituting:
![\begin{gathered} t=\frac{9\pm\sqrt[]{81-4(2)(-18)}}{2(2)} \\ t=\frac{9\pm\sqrt[]{81+144}}{4} \\ t=\frac{9\pm\sqrt[]{225}}{4} \\ t=\frac{9\pm15}{4} \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20t%3D%5Cfrac%7B9%5Cpm%5Csqrt%5B%5D%7B81-4%282%29%28-18%29%7D%7D%7B2%282%29%7D%20%5C%5C%20t%3D%5Cfrac%7B9%5Cpm%5Csqrt%5B%5D%7B81%2B144%7D%7D%7B4%7D%20%5C%5C%20t%3D%5Cfrac%7B9%5Cpm%5Csqrt%5B%5D%7B225%7D%7D%7B4%7D%20%5C%5C%20t%3D%5Cfrac%7B9%5Cpm15%7D%7B4%7D%20%5Cend%7Bgathered%7D)
We have two possible answers:

We only accept the positive answer because the time cannot be negative.
Now calculate the position for t = 6: