Answer: sin u = -5/13 and cos v = -15/17
Step-by-step explanation:
The nice thing about trig, a little information goes a long way. That’s because there is a lot of geometry and structure in the subject. If I have sin u = opp/hyp, then I know opp is the opposite side from u, and the hypotenuse is hyp, and the adjacent side must fit the Pythagorean equation opp^2 + adj^2 = hyp^2.
So for u: (-5)^2 + adj^2 = 13^2, so with what you gave us (Quad 3),
==> adj of u = -12 therefore cos u = -12/13
Same argument for v: adj = -15,
opp^2 + (-15)^2 = 17^2 ==> opp = -8 therefore sin v = -8/17
The cosine rule for cos (u + v) = (cos u)(cos v) - (sin u)(sin v) and now we substitute: cos (u + v) = (-12/13)(-15/17) - (-5/13)(-8/17)
I am too lazy to do the remaining arithmetic, but I think we have created a way to approach all of the similar problems.
Answer:
For a monthly cost of at least $7 and at most $8, you can have between 100 and 110 calling minutes.
Step-by-step explanation:
The problem states that the monthly cost of a celular plan is modeled by the following function:
In which C(x) is the monthly cost and x is the number of calling minutes.
How many calling minutes are needed for a monthly cost of at least $7?
This can be solved by the following inequality:
For a monthly cost of at least $7, you need to have at least 100 calling minutes.
How many calling minutes are needed for a monthly cost of at most 8:
For a monthly cost of at most $8, you need to have at most 110 calling minutes.
For a monthly cost of at least $7 and at most $8, you can have between 100 and 110 calling minutes.
10%
200 x x%=20
x=10%
Do u understand ?
Answer:
3)x=-9
4)x=-2
5)x=-4
6)x=-5
7)x=-12
8)x=-11
Step-by-step explanation:
You can write two equations using the given information:
.. L = W +8
.. L * W = 609
Using substitution, you get a quadratic.
.. (W +8) * W = 609
.. W^2 +8W -609 = 0
Not surprisingly, you're looking for factors of 609 that differ by 8.
.. 609 = 1*609 = 3*203 = 7*87 = 21*29
The last two are the factors of interest.
.. (W +29)(W -21) = 0
The width of the rectangle is 21 feet, the length is 29 feet.
_____
Sometimes it is easier to work with the average dimension. Here, let that be x. Then you have
.. (x +4)(x -4) = 609
.. x^2 -16 = 609
.. x^2 = 625 = 25^2 . . . . . . . one of your memorized math facts
So, the dimensions are
.. 25 +4 = 29 by 25 -4 = 21, that is, 29 ft by 21 ft.
