Question

cos(sinx)=1 ...find all the solutions...help please...

Answer 1

Well, we can start off with knowing when does cosine = 1?

Answer 2

when...uhm...i..dont know...

Answer 3

oh wait

Answer 4

90 degrees

Answer 5

270 degrees too

Answer 6

in radians?

Answer 7

Not for cosine, no. Thats when sin is 1 and -1.

Answer 8

ok :/

Answer 9

but cosine is 0 on both...:/

Answer 10

Ah, sorry, my brain is reversing it

Answer 11

so i had it right?

Answer 12

Whoa, whoa, we want to know when cosine = 1, not when itequals 0. Thats whatI wastrying to ask.

Answer 13

ok..so cosine equals one at...pi and zero

Answer 14

Exactly. So cos(pi) and cos(0) = 1, which means you haveto find values for sin x where it'lll equal pi or 0.

Answer 15

how do i do that...

Answer 16

The same way you knew where cosine was 0 :3. Its just this time we want to know where sin is 0 or sin is pi.

Answer 17

so 90 and 270? degrees...not radians

Answer 18

i looked at the unit circle...idk

Answer 19

Well, Id assume itd want the answer in radians. But yes, 90 degrees and 270 degrees is correct. Which would be pi/2 and 3pi/2. As for the second part, sin is never equal to pi. The range of the sin function is [-1,1], so finding sin x = pi is impossible.

Answer 20

ok...well i looked at the actual answer and i dont think its right :/ or i just still dont follow :/

Answer 21

Wow, my brain is reversing it. Rob will correct me.

Answer 22

npi, n=0, pos/neg 1,and 2

Answer 23

x = 0 by inspection.
Sin[0]=0
Cos[0]=1

Answer 24

what

Answer 25

We need sin x to equal 0, that way we can say cos(0) = 1. Sin x is 0 at the angles 0 and pi. So those two should be your answer. *hits head so it'll work*

Answer 26

but then how is one and two the answer..

Answer 27

I do not see how they could be with the given information.

Answer 28

so i should contact my teacher...eh?

Answer 29

Well, think of it this way, if x = 1 or 2, then sin(1) and sin(2) have to = 0.

Answer 30

A plot is attached.

Answer 31

That graph would include pi as well, it just starts to cut off there.

Answer 32

that didnt help me...but thank you @robtobey

Answer 33

But no, I see no way it can be 1 or 2 personally. Can you see why sinx onsode the parenthesis would have to be 0?

Answer 34

*inside

Answer 35

no not really :/

Answer 36

Alright.
Lets pretend sin x = y
Therefore cos(y) = 1
This is true when y = 0
So if y must be 0 and sin x = y, then we need to have sin x = 0.
Sin x = 0 when x is 0 or pi.

Answer 37

ok...quick question...do you know that cos(0)is one like by memory?

Answer 38

Pretty much. Its amazing how much Ive had to use that unit circle. For other random units like 5pi/6 or something, I have a way that helps me remember them.

Answer 39

alright. I think I understand the point youre trying to make/have made. thank you

Answer 40

Yeah, sure. And there is a way to remember the unit circle. Apart from the x axis and y axis, the values for sin and cos have a pattern that can be remembered.

Answer 41

alright, thank you

Answer 42

Good luck :3