Найди длину окружности ее диаметр равен 15дм. Число пи округлите до десятых

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1. Cars ... people great freedom of travel at present.

a) had given c) give

b) has given d) gave

2. Tomas Edison produced the first ... telephone.

a) work       c) working

b) worked       d) works

3. At Cambridge, Newton ... with great interest the writings of Galileo.

a) was read c) have read

b) read       d) to read

4. The unit of electricity "farad" ... after M. Faraday.

a) named       c) was named

b) will be named d) to be named

5. Metals are ... materials.

a) malleable c) elastic

b) brittle       d) precious

6. Glass and ceramics are ... materials.

a) brittle       c) elastic

b) ductile       d) malleable

7. Knowledge of materials properties is extremely important for ... .

a) teachers        c) engineers

b) managers d) computer programmers

8. Computer programmers create ... .

a) goods        c) telephone systems

b) hardware d) new software

9. Analogue signal ... transformed into digital one.

a) can       c) could

b) can be       d) could be

10. The first electric lamp ... in 1873 by A.N. Ladygin.

a) invented c) were invented

b) was invented d) was invent

11. Read the text below.

Humans have learnt many things from nature. These things have helped us in our daily life. The latest thing is self-repairing clothing. Scientists have developed a special way for clothing to repair rips and tears by itself, without the need for sewing. It works with materials such as cotton, linen and wool. The scientists are from the Naval Research Office and Pennsylvania State University in the USA. Scientists Dr. Walter Dressick and Dr Melik Demirel looked at how squid can cling on to things so well. The research team found a protein in the rings of teeth that cover the suckers on a squid. The protein is similar to the one found in the silk that spiders use to make spider webs. It is very strong and elastic (stretchy).

The new protein has been developed as part of a coating, which is put on clothes. When the coating is dipped in water, the area around the rip or tear joins together in less than a minute. This could help clothes last longer and save us money. It could also be useful for military and survival clothes. People like soldiers and mountaineers would be safer if they had clothes that repaired quickly and easily. Professor Demirel spoke about the invention. He said: "The coatings are thin, less than a micron, so they wouldn't be noticed in everyday wear." He added: "Even thin, they increase the overall strength of the material. For the first time, we are making self-healing textiles."

Answer the questions.

1) What must people dip the coating in for it to repair?

a) water

b) the sea

c) chemicals

2) How long does it take for a rip or tear to join together?

a) less than a minute

b) an hour or so

c) just seconds

3) What could the new invention save us?

a) time

b) headaches

c) money

4) How thin are the coatings that are put on clothes?

a) just over a micron

b) about a micron

c) less than a micron

Есть фанера размером 1525х1525мм, их 3 штуки

Из них сделали 20 полок для стеллажа

Вопро: какой размер 1 полки