Answer:
1926cm²
Step-by-step explanation:
Given
Dimension = 21cm by 18cn by 15cm
<em>The illustration in this question is to determine the surface area of the fabric and this is calculated using the surface area of a cuboid as follows:</em>
<em></em>
![Surface\ Area =2(LB + LH + BH)](https://tex.z-dn.net/?f=Surface%5C%20Area%20%3D2%28LB%20%2B%20LH%20%2B%20BH%29)
Where L, B and H are the dimensions.
So,
![Surface\ Area = 2(21 * 18 + 21 * 15 + 18 * 15)](https://tex.z-dn.net/?f=Surface%5C%20Area%20%3D%202%2821%20%2A%2018%20%2B%2021%20%2A%2015%20%2B%2018%20%2A%2015%29)
![Surface\ Area = 2(378 + 315 + 270)](https://tex.z-dn.net/?f=Surface%5C%20Area%20%3D%202%28378%20%2B%20315%20%2B%20270%29)
![Surface\ Area = 2(963)](https://tex.z-dn.net/?f=Surface%5C%20Area%20%3D%202%28963%29)
![Surface\ Area = 2 * 963](https://tex.z-dn.net/?f=Surface%5C%20Area%20%3D%202%20%2A%20963)
![Surface\ Area = 1926cm\²](https://tex.z-dn.net/?f=Surface%5C%20Area%20%3D%201926cm%5C%C2%B2)
<em>Hence, 1926 cm² of fabrics are needed to cover all surfaces.</em>
Depends on where you are in the math book but this would be the most simple way.
n= number
sqar(-1) = i
We have:
![cot(-x)cos(-x)+sin(-x)=-\frac{1}{f(x)}](https://tex.z-dn.net/?f=cot%28-x%29cos%28-x%29%2Bsin%28-x%29%3D-%5Cfrac%7B1%7D%7Bf%28x%29%7D)
Then we use trigonometric identities to change the negative sign of the trigonometric functions, so:
![-sin(x)-cot(x)cos(x)=-\frac{1}{f(x)}](https://tex.z-dn.net/?f=-sin%28x%29-cot%28x%29cos%28x%29%3D-%5Cfrac%7B1%7D%7Bf%28x%29%7D)
We clear f(x):
![f(x)=\frac{1}{sin(x)+cot(x)cos(x)}=\frac{1}{sin(x)+\frac{cos(x)}{sin(x)}cos(x)}=\frac{1}{sin(x)+\frac{cos^2(x)}{sin(x)}}](https://tex.z-dn.net/?f=f%28x%29%3D%5Cfrac%7B1%7D%7Bsin%28x%29%2Bcot%28x%29cos%28x%29%7D%3D%5Cfrac%7B1%7D%7Bsin%28x%29%2B%5Cfrac%7Bcos%28x%29%7D%7Bsin%28x%29%7Dcos%28x%29%7D%3D%5Cfrac%7B1%7D%7Bsin%28x%29%2B%5Cfrac%7Bcos%5E2%28x%29%7D%7Bsin%28x%29%7D%7D)
we simply what we can:
![f(x)=\frac{1}{\frac{sin^2(x)+cos^2(x)}{sin(x)}}=sin(x)](https://tex.z-dn.net/?f=f%28x%29%3D%5Cfrac%7B1%7D%7B%5Cfrac%7Bsin%5E2%28x%29%2Bcos%5E2%28x%29%7D%7Bsin%28x%29%7D%7D%3Dsin%28x%29)
Thus, the correct answer is;
Triangle 1 area : 6×4 /2 -> 24/2 -> 12
triangle 2 area : 9×8 /2 -> 72/2 -> 36
rectangle 1 area : 6×4 -> 24
rectangle 2 area : 15×4 -> 60
12+36+24+60
48+24+60
72+60
132
Answer: 16
Step-by-step explanation: