Answer:
Part I: cot(15 degrees) = cot(45 - 30)
Part II: Evaluation is below
Step-by-step explanation:
<em>Everything is done in degrees</em>
<em />
Two angles that differ by 15 degrees that is easy to evaluate is 30 degrees and 45 degrees. The cot(15 degrees) = cot(45 - 30) = 1/tan(45-30) = (1+tan45tan30)/(tan30 - tan45) = (1+ sqrt(3))/(sqrt(3) - 1)
We rationalize this by multiplying 1+ sqrt(3) in the top and bottom, getting:
(4 + 2sqrt(3))/2 = 2 + sqrt(3)
I hope this helps! :)
Sn = n/2 (a1+an)
= 8/2 (3-38)
= 4 (-35)
= -140
What you would do is multiply 72 and 3 so it says three times so you multiply 72 three times so this would equal 638
$10 / 8 = 1.25
Soo...
$6 x 1.25 = 7.50
Start by writing the system down, I will use 
to represent 
Substitute the fact that 
into the first equation to get,
Simplify into a quadratic form (
),
Now you can use Vieta's rule which states that any quadratic equation can be written in the following form,
which then must factor into
And the solutions will be 
.
Clearly for small coefficients like ours 
, this is very easy to figure out. To get 5 and 6 we simply say that 
.
This fits the definition as 
and 
.
So as mentioned, solutions will equal to but these are just x-values in the solution pairs of a form 
.
To get y-values we must substitute 3 for x in the original equation and then also 2 for x in the original equation. Luckily we already know that substituting either of the two numbers yields a zero.
So the solution pairs are 
and 
.
Hope this helps :)
