Master Wang made a light box with 78.5 square centimeters of openings in the middle of the top and bottom. How much colored paper did he use? 20cm in diameter

Master Wang made a light box with 78.5 square centimeters of openings in the middle of the top and bottom. How much colored paper did he use? 20cm in diameter

Sword shadow remnant C dance,
Bottom radius: 20 △ 2 = 10 (CM)
Bottom area: 3.14 × 10 × 10 = 314 (cm2)
Side area: 3.14 × 20 × 30 = 1884 (cm2)
Common color paper: 1884 + (314-78.5) × 2 = 2355 (square centimeter)

[a cylinder is composed of three planes] [b cylinder is surrounded by two planes, one is flat and the other is curved] [C ball is surrounded by one plane] [D cube is surrounded by six planes] which pair

First of all, a is wrong, two planes and a curved surface, so B is also wrong. The ball can't be surrounded by planes, so only D is correct

A simple math problem ~ speed
A & sup3; B + (A & sup3; b-2c) - 2 (A & sup3; B-C) please explain in detail, thank you~
Another question: 2 (A & sup3; B-C) = 2A & sup3; b-2c or = 2A & sup3; · 2b-2c?

Original formula = A & sup3; B + A & sup3; b-2c-2 (A & sup3; B-C)
=2a³b-2c-2a³b+2c
=0
It should be 2 (A & sup3; B-C) = 2A & sup3; b-2c

I want a computer as a birthday present

I'd like a computer as my birthday present.

How do five eights equal 12

88/8+8/8=12

If the value of the square of 3Y - 2Y + 6 is 8, then the square of two thirds of 3Y - y + 1 =?

The square of 3Y - 2Y + 6 = 8
The square of 3Y - 2Y = 2
Divide two sides by two
The square of 2 / 3Y - y = 1
So the square of 3 / 2 y - y + 1 = 1 + 1 = 2

What English words begin with e?

Income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income, income

Shen, Liu and Zhou are teachers of Chinese, mathematics and foreign languages respectively. It is known that each teacher teaches only one course. In addition, they also know the following: A. Mr. Shen
B. the foreign language teacher is a student's brother; C. Miss Zhou is a woman, she asked a question to the math teacher

Professional teacher answers for you. (knowledge is power!) Mr. Shen teaches (foreign language) Mr. Liu teaches (Mathematics) Mr. Zhou teaches (Chinese) reason: Mr. Shen uses foreign language in class, so he teaches foreign language. Mr. Zhou asks questions to math teacher, explaining that he either teaches Chinese

Let y = y (x) be determined by tany = Y-X, then dy =?

tany=y-x
The derivation of X on both sides is: sec & # 178; y * y '= y' - 1
So y '= - 1 / (SEC & # 178; Y-1) = - 1 / Tan & # 178; y
So dy / DX = - 1 / Tan & # y
That is dy = - DX / Tan & # y
If you don't understand, I wish you a happy study!

69 and 16 / 19 × (- 9)

69 16 / 19 × (- 9)
=(70-3/19)×(-9)
=70×(-9)-3/19×(-9)
=-630+27/19
=-628 11 / 19