The main identity you need is the double angle one for cosine:

We get

Expand the numerator to apply the identity again:




Finally, make use of the product identity for cosine:

so that ultimately,


Part C:
y = total cost
M = minutes
You can talk on the phone only 100 minutes per month
Company A:
y = 0.04M + 5
y = 0.04(100) + 5
y = 4 + 5
y = 9 $9 per month
Company B:
y = 0.10M + 2
y = 0.10(100) + 2
y = 10 + 2
y = 12 $12 per month
Company A offers the best deal because at Company A you have to pay $9 for 100 minutes per month, and at Company B you have to pay $12 for 100 minutes per month, so you have to pay $3 less.
Part D:
1.) With a budget of $30, Company A would allow me to talk longer on the phone. I know this because for Company A, you pay $3 less per month for the same amount of minutes as Company B. This means that I will save more money with Company A, and I can buy more minutes. (something like this)
Hello :
cscx = -5/2
1/sinx =-5/2
sinx=-2/5
sin²x+cos²x=1
4/25+cos²x=25/25
cos²x = 21/25
between 270 and 360 : cosx > 0 cosx=(<span>√21)/5
but : sin2x =2sinx cosx
sin2x = 2(-2/5)(</span>(√21)/5)
sin2x = (-4√21)/25
The answer could vary depending on the information your individual lesson is using for the population/debt. However, an answer that should be close (or possibly exact) is $16,527.39 per person.
Answer:
Yeah.it is right
Step-by-step explanation: