Sundial Math Equations

[sguk]

Hi, can someone please help with me with the following:

I have an old book on sundial which dates to the pre-calculator age, which contains formulas I need to have in my java program to write a visual sundial designer. Now the problem is i cant understand some of the equations as my maths is a bit rusty.

the first equation is

log tan SD = log sin T + log cot P ...

where SD is a value that needs to be found, T and P are arbitrary values.
I have been able to work out SD like this .. SD = ArcTangent( Sin T * Cot P)
which gives me the right answer .. .

now im stuck with the following equation:

log cot DL = log cot T + log sin P

i dont how to find dl for the above equation can someone plz provide me some tips .. id really appreciate it iv been stuck trying to solve this for 3 days ..

[VBAhack]

Welcome to the forums.

Since Cot x = 1/Tan x, if I'm not mistaken, it goes like this:

Cot DL = Cot T * Sin P

Tan DL = 1 / (Cot T * Sin P)

DL = ArcTan[ 1 / (Cot T * Sin P) ]

[sguk]

omg brilliant .. just did that on the calculator and got the same answer as was in the book thanks a lot heheh now i can carry on i just cudnt work it out ... its been ages since i did trig stuff

[sguk]

Welcome to the forums.

Since Cot x = 1/Tan x, if I'm not mistaken, it goes like this:

Cot DL = Cot T * Sin P

Tan DL = 1 / (Cot T * Sin P)

DL = ArcTan[ 1 / (Cot T * Sin P) ]

hey thanks a lot its just all this i couldnt figure out yeah this gave me the right answer as was in the book thanks youu

[sguk]

thank you .... now i can program this .. what you have worked out gives the right answer as given in my sundial book but i couldnt figure out how it got it ... thanksss