<h3>
Answer:</h3>
a. -(3√13)/13
<h3>
Step-by-step explanation:</h3>
The cosine can be found from the tangent by way of the secant.
tan(θ)² +1 = sec(θ)² = 1/cos(θ)²
Then ...
cos(θ) = ±1/√(tan(θ)² +1)
The <em>cosine is negative in the second quadrant</em>, so we will choose that sign.
cos(θ) = -1/√((-2/3)² +1) = -1/√(4/9 +1) = -1/√(13/9)
cos(θ) = -3/√13 = -(3√13)/13 . . . . . matches your selection A
Answer:
y = -7 and x = -36
Step-by-step explanation:
x - 4y = -8
5y - 1 = x
→ Substitute 5y - 1 into x - 4y = -8
5y - 1 - 4y = -8
→ Simplify
y - 1 = -8
→ Add 1 to both sides
y = -7
→ Substitute y = -7 into 5y - 1
( 5 × -7 ) - 1 = -36
Answer:
40 inches
Step-by-step explanation:
We know that the height of water in a pool decreased 5 inches per week.
This means that we can form the equation 
, since the amount of water remaining is proportionate to the amount of weeks that have passed.
We know 
, since we need to find the change for 8 weeks.
The change will be the absolute value of -40, which just makes it positive, so 40.
Hope this helped!
