Answer:
 
Step-by-step explanation:
If a complex number is z=a+ib, then the trigonometric form of complex number is
 
where,  and
 and  ,
,  is called the argument of z,
 is called the argument of z,  .
.
The given complex number is -5i.
It can be rewritten as
 
Here, a=0 and b=-5.  lies in 4th quadrant.
 lies in 4th quadrant.
 
 
 
 
    ![[\because \text{In 4th quadrant }\theta=2\pi-\theta]](https://tex.z-dn.net/?f=%5B%5Cbecause%20%5Ctext%7BIn%204th%20quadrant%20%7D%5Ctheta%3D2%5Cpi-%5Ctheta%5D) 
 
So, the trigonometric form is
 
 
        
                    
             
        
        
        
Answer:
There are 84 total boats. 
Step-by-step explanation:
In order to find this, we first need to find the fraction which are red. We can do this by multiplying the whole by how many are not white. 
1 * 1/4 = 1/4
Now we take that amount and multiply it by the amount that are not blue of the remaining. 
1/4 * 3/7 = 3/28 
Now that we have this, and we know this is 9 boats, we can divide 9 by this fraction and it will give us the total number of boats. 
9 ÷ 3/28 = 84
 
        
             
        
        
        
Answer:
0.0009
Step-by-step explanation:
 
        
             
        
        
        
Answer:
h(t) = -16t2 + 144
 
h(1) = -16(12) + 144 = 128 ft
h(2) = -16(22) + 144 = 80 ft
 
h(2) - h(1) = 80 - 128 = -48 ft
 
It fell 48 ft between t = 1 and t = 2 seconds.
 
It reaches the ground when h(t) = 0
 
0 = -16t2 + 144
t = √(144/16) s = 3s
It reaches the ground 3s after being dropped.
 Step-by-step explanation: