A piece of paper has a
1 answer:
Answer:
The volume of the resulting cylinder is 385 cm³
Step-by-step explanation:
The formula of the rule of a cylinder is V = π r² h, where
- r is the radius of its base
- h is the height of it
<em>When a rectangular paper folded to form a cylinder, then one of its dimension will be the circumference of the base and the other dimension will be the height of the resulted cylinder</em>
∵ ABCD is a rectangle
∵ It is folded where AB coincides with DC
∴ AB is the height of the resulted cylinder
∴ BC is the circumference of the base of the resulted cylinder
∵ AB = 10 cm
∴ h = 10 cm
∵ BC = 22 cm
∴ The circumfrence of the base = 22 cm
∵ The circumference of a circle = 2 π r
→ Equate the rule by 22 to find r
∴ 2 π r = 22
∵ π =
∴ 2 × × r = 22
∴ r = 22
→ Divide both sides by
∴ r = 3.5 cm
→ Use the formula of the volume above to find the volume of the cylinder
∵ V = × (3.5)² × (10)
∴ V = 385 cm³
∴ The volume of the resulted cylinder is 385 cm³
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Hello,
r=5(1+cos t)
r'=5(-sin t)
r²+r'²= 25[(1+cos t)²+(-sin t)²]=50(1-cos t)=50 sin² (t/2)
Between 0 and π, sin x>0 ==>|sin x|=sin x
![l= 2*5* \int\limits^{\pi}_0{sin( \frac{t}{2} )} \, dt= 5[-cos (t/2)]_0^{\pi}\\\\ =5(0+1)=5](https://tex.z-dn.net/?f=l%3D%202%2A5%2A%20%5Cint%5Climits%5E%7B%5Cpi%7D_0%7Bsin%28%20%5Cfrac%7Bt%7D%7B2%7D%20%29%7D%20%5C%2C%20dt%3D%205%5B-cos%20%28t%2F2%29%5D_0%5E%7B%5Cpi%7D%5C%5C%5C%5C%0A%3D5%280%2B1%29%3D5)
Here is the method but i may have make some mistakes.
r=5(1+cos t)
r'=5(-sin t)
r²+r'²= 25[(1+cos t)²+(-sin t)²]=50(1-cos t)=50 sin² (t/2)
Between 0 and π, sin x>0 ==>|sin x|=sin x
Here is the method but i may have make some mistakes.