Answer:

Step-by-step explanation:
Given

Required
Use the expression to prove a trigonometry identity
The given expression is not complete until it is written as:

Going by the Pythagoras theorem, we can assume the following.
- a = Opposite
- b = Adjacent
- r = Hypothenuse
So, we have:


Having said that:
The expression can be further simplified as:

Substitute values for sin and cos
becomes

Answer:
7000
Step-by-step explanation:
This is because when you round to the significant figure, you basically look at any digits at the start of the number, which isn't zero. In this case, it would be in the thousands place 7284. So you round 7284 to the nearest thousands, which, would be 7000
Answer:
The correct option is;
D. x = -1.38 and 0.82
Please find attached the combined function chart
Step-by-step explanation:
The given equation is x³ + 3 = -x⁴ + 4
Plotting the equation using Excel, we have;
f(x) = x³ + 3, h(x) = -x⁴ + 4
x f(x) h(x)
-1.4 0.256 0.1584
-1.39 0.314381 0.26699
-1.38 0.371928 0.373261
-1.37 0.428647 0.477246
-1.36 0.484544 0.57898
Which shows an intersection at the point around -1.38
x f(x) h(x)
0.77 3.456533 3.64847
0.78 3.474552 3.629849
0.79 3.493039 3.610499
0.8 3.512 3.5904
0.81 3.531441 3.569533
0.82 3.551368 3.547878
0.83 3.571787 3.525417
Which shows the intersection point around 0.82
Therefore, the correct option is x = -1.38 and 0.82
From the graphing calculator the intersection point is given as
x = -1.3802775691 and 0.81917251339.
From the information we have, we know that each book costs 1.20 dollars. So we shall say this price is at 100% .
Now we need to form an equation to get the percentage when the books are sold at 0.80 dollars.
100% = 1.20
x = 0. 80
Where x is the new percentage when the sale is at 0.80 dollars.
We cross multiply the equation:
1.20 *x = 0.80 * 100
1.2x = 80
x = 80/1.2
x = 66.7%
Round off 66.7 to the nearest tenth we get 67%
The notebooks are sold at 67% (of the original cost).