Answer: option B. 4 feet above water.
Explanation:
This is an example of the use of the integer numbers.
Integer numbers are positive, zero and negative numbers.
In this case, zero is used to represent the surface of the water. So, any positive number will be the position above water and any netative number will be the position below water. That is why, while - 4 represents the position of the dolphin below water, 4 represents the position 4 feet above water.
Sinusoidal equations are trigonometric functions involving sine and cosine functions. Graphically, they look like wave patterns having amplitudes and periods. The general form of a sinusoidal equation is
y = A sin(Bx + C) + D
where
A = amplitude
B = frequency
C = shift on starting angle
D = shift of wave on the y-axis
From the given problem, A = 1 and D = 3. There is no value for C because there is no mention of any shift in angle. About the frequency, you can obtain this by getting the reciprocal of the period. Thus, B = 2/π. The complete equation is
y = sin(2x/π) + 3
Try this solution (the way shown is not the shortest one):
The task on the left part:
1. note, the point P and R have coordinates (-4;-4) and (-3;-2).
2. using the coordinates of points P and R it is possible to make up the equation of the required line:
The task of the right part:
1. note, the common view of the equation of the line is y=kx+b, where b - an intersection point of the Y-axis and the given line; k=QR/PQ.
2. according the picture b= -5, k=4/1=5, so <u>y= -4x-5</u>
