Предмет: Математика, автор: NEsabudka

sin (2x - 2) = sin2x - sin2 сумма корней в радианах на отрезке [0; 360]

Ответы

Автор ответа: nVikki
0
sin(2x-2)=2sin(x-1)*cos(x-1)
sin2x-six2=2sin(x-1)*cos(x+1)
2sin(x-1)*cos(x-1)=2sin(x-1)*cos(x+1)
sin(x-1)*cos(x-1)-sin(x-1)*cos(x+1)=0
sin(x-1)*(cos(x-1)-cos(x+1))=0
sin(x-1)=0;    cos(x-1)-cos(x+1)=0
x-1=pi*n ;      cosx*cos1+sinx*sin1-cosx*cos1+sinx*sin1=0
x=1+pi*n;          2sinx*sin1=0
                         sinx=0
                           x=pi*k
[0; 2*pi]                      [0;2*pi]
x=1+pi*n                    x=pi*k
n=0, x=1.                     k=0, x=0
n=1, x=1+pi                  k=1, x=pi,
                                    k=2, x=2*pi
Ответ: 0, 1, pi, 1+pi, 2pi, 





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Exercises

Unit

3Are the underlined verbs OK? Correct them where necessary.

1 Water boils at 100 degrees Celsius. OK

2 How often are you going to the cinema? do you go

3 Ben tries to find a job, but he hasn’t had any luck yet...................................

4 Martina is phoning her mother every day.......................................................

5 The moon goes round the earth in about 27 days............................................

6 Can you hear those people? What do they talk about?...................................

7 What do you do in your spare time?................................................................

8 Sarah is a vegetarian. She doesn’t eat meat....................................................

9 I must go now. It gets late...............................................................................

10 ‘Come on! It’s time to leave.’ ‘OK, I come.’.....................................................

11 Paul is never late. He’s always starting work on time.........................................

12 They don’t get on well. They’re always arguing...................................................

Put the verb into the correct form, present continuous or present simple.

1 a I usually get (I / usually / get) hungry in the afternoon.

b I’m getting (I / get) hungry. Let’s go and eat something.

2 a ................................‘ (you / listen) to the radio?’ ‘No, you can turn it off.’

b ..................................‘ (you / listen) to the radio a lot?’ ‘No, not very often.’

3 a The River Nile ..............................(flow) into the Mediterranean.

b The river................................. (flow) very fast today – much faster than usual.

4 a I’m not very active............................................ (I / not / do) any sport.

b What......................................... (you / usually / do) at weekends?

5 a Rachel is in New York right now. ..............................................(She / stay) at the Park Hotel.

b ....................................................(She / always / stay) there when she’s in New York.

3 Put the verb into the correct form, present continuous or present simple.

1 Why are all these people here? What’s happening (What / happen)?

2 Julia is good at languages. .............................................(She / speak) four languages very well.

3 Are you ready yet? .........................................................(Everybody / wait) for you.

4 I’ve never heard this word. How ........................................(you / pronounce) it?

5 Kate..................................................... (not / work) this week. She’s on holiday.

6 I think my English ..............................................(improve) slowly. It’s better than it was.

7 Nicola .........................................(live) in Manchester. She has never lived anywhere else.

8 Can we stop walking soon?.............................................. (I / start) to get tired.

9 Sam and Tina are in Madrid right now. .................................................(They / visit) a friend of theirs.

10 ‘What....................................................... (your father / do)?’ ‘He’s an architect.’

11 It took me an hour to get to work this morning. Most days.............................................................

(it / not / take) so long.

12 I ...................................................................(I / learn) to drive. My driving test is next month. My father (teach) me.