How to Use a Sundial to Find Latitude

[itsastruggle]

Homework Statement

Use the graph (attached) to find the latitude of your observing location. Show your calculation on how to derive the latitude.

Homework Equations

The angle of elevation at noon has been calculated as 49.5$$\circ$$.
The data was recorded on the 2nd of May (42 days after the 21st March).

The Attempt at a Solution

My attempt involved estimating on the graph what angle would be given for 42 days (after March 21st). This gave me an estimation of 20$$\circ$$. I then subtracted this angle from 49.51$$\circ$$.

49.51-20 = 29.51$$\circ$$

Is that correct? I don't think it is, because it's based on a really rough estimation using the graph. Is there a calculation that I can do to find an accurate answer for the latitude?

Please help! Thanks!

 

[QuarkCharmer]

Did you take the 49.5 deg at noon measurement yourself? If so, you should be able to determine how close you are to a correct solution by checking a map such as this one:
[PLAIN]http://www.hightunnels.org/images/latitude%20and%20Longitude%20Map.gif

I can't believe they didn't give you a function for that sine wave. There is practically no information on the X-axis, those points could be 1/2 days for all we know.

 

[itsastruggle]

Yes the 49.5 degree noon measurement was taken myself.

No they didn't give me any other information, nor a function for the sine wave...

That's why I'm confused as to what they want me to do when they say "show your calculation on how to derive the latitude".