Convert sin to cos

[mathstudent4578]

I am having trouble converting this equation from a sin to cos equation.

f(x)=1.716sin(pi/386(x))+2.27

 

[Dr.Peterson]

I am having trouble converting this equation from a sin to cos equation.

f(x)=1.716sin(pi/386(x))+2.27

If you mean that you want to make a function based on the cosine rather than the sine, that is equivalent to this one, then you need a 90 degree phase shift. Does that sound familiar? This is because (among other things) sin(x) = cos(x - pi/2).

Please show us what you tried, and what you have learned about sine and cosine graphs, so we can better see what sort of help you need. If this is an exercise you were assigned, show us the actual wording, and perhaps an example you may have been given.

 

[mathstudent4578]

Yes the 90 degree phase shift is what I was attempting. However, I was struggling with converting the values.

When converting, am I supposed to do pi/2 + pi/386? Since that is my "B" value?

The graph of my sin equation looks like this:



The instructions are to find another trigonometric model based off the sin function that I was able to find.

 

[Steven G]

Does your cosine graph look exactly the same?

Did you follow Dr Peterson's suggestion about using sin(x) = cos(x - pi/2)??

 

[mathstudent4578]

I am not sure yet because I the conversion between the two is not making sense. I just need help converting the sine equation to a cosine equation.

Which value do I plug into the cos(x-pi/2) and how do I find the phase shift?

 

[Deleted member 4993]

I am having trouble converting this equation from a sin to cos equation.

f(x)=1.716sin(pi/386(x))+2.27

Can you plot f(x) = 1.716*sin(π/386 * x) + 2.27?

Now plot f(x) = 1.716*cos(π/2 - π/386 * x) + 2.27

What difference/similarity do you observe?