If you meant to say 3^5 or
, then,
(there are five copies of '3' multiplied)
So the answer would be choice D) 243.
Answer: The director can choose first a lead singer and then a stand-in for the lead singer in 132 ways.
Step-by-step explanation:
Given : The total number of singers auditioning for the school musical.= 12
The director wanted choose first a lead singer and then a stand-in for the lead singer.
We use Permutations here because order of selecting the singers matters.
The number of permutations of selecting r things out of n things = ![^nP_r=\dfrac{n!}{(n-r)!}](https://tex.z-dn.net/?f=%5EnP_r%3D%5Cdfrac%7Bn%21%7D%7B%28n-r%29%21%7D)
Similarly , the number of ways to select 2 singers in an order from 12 singers
![^{12}P_{2}{=\dfrac{12!}{(12-2)!}](https://tex.z-dn.net/?f=%5E%7B12%7DP_%7B2%7D%7B%3D%5Cdfrac%7B12%21%7D%7B%2812-2%29%21%7D)
![=\dfrac{12\times11\times10!}{10!}=132](https://tex.z-dn.net/?f=%3D%5Cdfrac%7B12%5Ctimes11%5Ctimes10%21%7D%7B10%21%7D%3D132)
Hence, the director can choose first a lead singer and then a stand-in for the lead singer in 132 ways.
Answer: -4/5
Step-by-step explanation:
Ok so cos(x) = -4/5 and we know that:
.
If we plug that in and solve for sin(x) we get:
![sin^2(x) = \frac{9}{25} \\sin(x) = \frac{3}{5}](https://tex.z-dn.net/?f=sin%5E2%28x%29%20%3D%20%5Cfrac%7B9%7D%7B25%7D%20%5C%5Csin%28x%29%20%3D%20%5Cfrac%7B3%7D%7B5%7D)
Now we have to consider: <em>is sin(x) positive or negative?</em>
We have that
.
From the unit circle, we know that sin(x) is negative in this range. Therefore sin(x) actually equals -3/5.
But the question asks: <em>what is
?</em>
Here's where another important equation comes in:
![sin(\alpha + \beta ) = sin(\alpha)cos(\beta) + cos(\alpha)sin(\beta)](https://tex.z-dn.net/?f=sin%28%5Calpha%20%20%2B%20%5Cbeta%20%29%20%3D%20sin%28%5Calpha%29cos%28%5Cbeta%29%20%2B%20cos%28%5Calpha%29sin%28%5Cbeta%29)
In this case, we have alpha = x and beta = pi/2.
So, that looks like:
sin(x + pi/2 )= sin(x)cos(pi/2) + cos(x)sin(pi/2)
We already have what sin(x) and cos(x) are. We also know that sin( pi/2) = 1 and cos(pi/2) = 0.
sin(x + pi/2 ) = (-3/5)(0) + (-4/5)(1).
Therefore we simply have
sin(x + pi/2) = -4/5
The variable z represents how many games that ella played during the season