A half cylinder is 10 cm in diameter and 40 cm in height. What's the surface area?

A half cylinder is 10 cm in diameter and 40 cm in height. What's the surface area?

What's the bottom area
(10 △ 2) × (10 △ 2) × 3.14 = 78.5 (square centimeter)
What is the area of the rectangle on the side
10 × 40 = 400 (cm2)
What is the area of the surface on the side
10 × 3.14 × 40 △ 2 = 628 (square centimeter)
What is the surface area
78.5 + 400 + 628 = 1106.5 (cm2)

The bottom radius of a cylinder is 5cm and its height is 10cm. Its surface area is______ And the volume is______ ．

2 × 3.14 × 52 + 2 × 3.14 × 5 × 10 = 2 × 3.14 × 25 + 3.14 × 100 = 3.14 × 50 + 314 = 157 + 314 = 471 (square centimeter); 3.14 × 52 × 10 = 3.14 × 25 × 10 = 3.14 × 250 = 785 (cubic centimeter). A: its surface area is 471 square centimeter and its volume is 785 cubic centimeter

If the height of a cylinder increases by 3 cm, the side area increases by 18.84 square cm. How much does the volume of the cylinder increase?

Bottom circumference = 18.84 △ 3 = 6.28cm
Radius = 6.28 ／ 2 ／ 3.14 = 1cm
Volume increase = 3.14 × 1 & # 178; × 3 = 9.42 cm3

The area of the bottom of the cylinder increases by 3.84 centimeters______ ．

The radius of this cylinder is: 18.84 △ 3 △ 3.14 △ 2 = 1 (CM), the bottom area of this cylinder is: 3.14 × 12 = 3.14 (square cm); answer: the bottom area of this cylinder is 3.14 square cm. So the answer is: 3.14 square cm

What is the English expression of the word "expression" in computer?

expression

The expression of multiple in English
There are three kinds of multiples, as... As, - er than,

A be x times the size / height... Of Ba be X-1 time bigger than Ba be c times as big as Ba be bigger than B by X-1 times

Can there be more than one and in an expression?
One hundred and one
What about 101101? It's one hundred and one thousand one hundred and one
Or one hundred one thousand one hundred and one
Is there only one and, or is it necessary to add and after hundred

The first one is right. You have to add any change

How to express a function or compound fraction expression in English?
such as
y=x+az/(c+x)
I don't need to translate the above function directly. What I want is the syntax of expression

function y equals to kx plus az over c plus x.
y=kx+az/(c+x)
The fraction is expressed as the numerator over denominator, and so is the composite

English multiple expression
One of them
Subject + predicate + multiple (or fraction) + as + adj. + as
Be sure to use adj
Can we use adv. or as adj. A / an n. as?

the earth is 49 times as big as the moon.big It's an adjective
If you want to use adverbs, you need to use verbs in front of them
a puma runs 5 time as fast as a deer.fast It's an adverb
As adj.a/an n.as did not understand as beautiful a girl as?
Mary is as beautiful as rose

Let's see what's wrong with the derivation of the surface area formula s = 4 π R & # 178,
I think the surface area of the ball can be sliced, cut a hemisphere, and then integrate the perimeter
S = 2 π∫ (0 to R) XDY
X & # 178; + Y & # 178; = R & # 178;, let x = RCOs θ, y = rsin θ, (0 ≤ θ ≤ π / 2)
S = 2 π∫ (0 to π / 2) RCOs θ D (rsin θ) = 2 π R & # 178; ∫ (0 to π / 2) cos & # 178; θ D θ
But in the end, s is not equal to 2 π R & # 178;, what's wrong with me? Is the method wrong? What's wrong with me?

As shown in the figure, the width of the ring you want to integrate should be the length of the hypotenuse dy / cos θ, not dy. substituting in, you get & nbsp; s = 2 π∫ (0 to π / 2) r d (rsin θ). I believe you can handle the rest by yourself