Begin with cos(θ) = 5/13, θ in Quadrant IV
you should distinguish the 5-12-13 right-angled triangle
and then cosØ = adjacent/hypotenuse
x = 5, r = 13 , y = -12, since Ø is in IV
and sinØ = -12/13
also tan(ϕ) = −√15 = -√15/1 = y/x and ϕ is in II,
y = √15 , x = -1
r^2 = x^2 + y^2 = 15+1 = 16
r = 4
sinϕ = √15/4 , cosϕ = -1/4
you must know that:
cos(θ − ϕ) = cosθcosϕ + sinθsinϕ
= (5/13)(-1/4) + (-12/13)(√15/4)
= -5/52 - 12√15/52
= (-5-12√15)/52
First let us calculate the total cost before tax:
1.06 * cost = 16.43
cost = 15.5
Therefore the cost of sunscreen is:
2 * Sunscreen + 6.50 = 15.5
2 * Sunscreen = 9
Sunscreen = $4.50
<span>Hence each bottle of sunscreen cost $4.50</span>
X=5
Do you need an explanation or is the answer enough?
The domain of that function is all real numbers because it's a line.
