It’s a good step because you know where you are at in present time as well as looking ahead into the future financially.
In this diagram we see that 80 and 3x+4y are both vertical angles and vertical angles are congruent or always equal so we can set those two equations equal to each other then we can see that a line splits two angles making them supplementary (they equal 180 degrees) So we can have another equation, the two equations are:
3x+4y=80 and 3x+4y+7x-8y=180 (add like terms to simplify and get 10x-4y=180
Then use elimination to get rid of the y variables
10x-4y=180 (plus)
+3x+4y=80 (the negative 4 and positive 4 cancels each other out so you are left with:)
13x=160 (divide by x)
x=12.30769 which can be rounded to x=12.31
Then we have to plug in x into the first equation:
3(12.31) + 4y = 80
36.93 + 4y = 80 (subtract 36.93 from 80)
4y = 43.07 (divide)
y=10.7675 or rounded to 10.77
so x=12.31 and y=10.77
Step-by-step explanation:
![\sin^{4}x \: - \cos^{4} x = (\sin^{2}x)^{2} - (\cos^{2}x)^{2}](https://tex.z-dn.net/?f=%5Csin%5E%7B4%7Dx%20%20%5C%3A%20%20-%20%20%5Ccos%5E%7B4%7D%20x%20%3D%20%28%5Csin%5E%7B2%7Dx%29%5E%7B2%7D%20%20-%20%28%5Ccos%5E%7B2%7Dx%29%5E%7B2%7D%20)
![= (\sin^{2}x)^{2} - (1 - \sin^{2}x)^{2}](https://tex.z-dn.net/?f=%20%3D%20%28%5Csin%5E%7B2%7Dx%29%5E%7B2%7D%20%20-%20%281%20-%20%5Csin%5E%7B2%7Dx%29%5E%7B2%7D%20)
![= \sin^{4}x - (1 - 2\sin^{2}x + \sin^{4}x)](https://tex.z-dn.net/?f=%20%3D%20%5Csin%5E%7B4%7Dx%20-%20%281%20-%202%5Csin%5E%7B2%7Dx%20%2B%20%5Csin%5E%7B4%7Dx%29)
![= 2\sin^{2}x - 1](https://tex.z-dn.net/?f=%20%3D%202%5Csin%5E%7B2%7Dx%20-%201)
![= - \cos2x](https://tex.z-dn.net/?f=%20%3D%20%20-%20%5Ccos2x)
Note: I used the identity
![{ \sin }^{2} x = \frac{1}{2} (1 - \cos \: 2x)](https://tex.z-dn.net/?f=%20%7B%20%5Csin%20%7D%5E%7B2%7D%20x%20%3D%20%20%5Cfrac%7B1%7D%7B2%7D%20%281%20-%20%20%5Ccos%20%5C%3A%202x%29)
for the last step.
PS. I love proving trigonometric identities!
The answer is 50% as half the circle is shaded!
Answer:
100
Step-by-step explanation: