Math Question

[Xenium]

Originally Posted by who is chris c

just a fyi you cant divide normal trig fnct (sin, cos, tan) by both sides like normal you need to take the inverse (^-1) to do the equalitive property been awhile but thought i'd throw that in

Didn't we already work that out?

[Adrian Schneider]

Originally Posted by Xenium

Me too.. F = SQUAREROOT(INVERSETAN(A/2))

@peterska2. The inverse of TAN is INVERSETAN not divide tan

A = 2(TAN(F*F))
A = 2(TAN(F^2))
A/2 = TAN(F^2)
INVERSETAN(A/2) = F^2
F = SQUAREROOT(INVERSETAN(a/2))

Didn't we already work that out? LOL just kidding

I wish our calculators were as easy to program with as PHP, it would have made math class so much easier...

[lightnb]

I'm using:

$FA = sqrt(rad2deg(atan($MFh/2)));

and getting '3.56' as the answer when $MFh is set to .45.

I should be getting "36 degrees". I think the decimal place may be off?

[lightnb]

My other equation isn't working right either...

I have the two variables, and depending on which one the user gives, it should solve for the other. but it seems that the answers don't work the other way:

for example if I set $FA and get an answer for $MFh, then use that answer to solve for $FA again, the answer i get isn't the number I started with.

the two equations are:

PHP Code:

$MFh=2*(tan($FA*$FA)); 


and

PHP Code:

$FA = sqrt(rad2deg(atan($MFh/2))); 


any ideas?

[lightnb]

I guess this has gone from a general math question, to a PHP syntax issue. Should it be moved to a different forum?

[Paul M]

AFAIK, in php both TAN and ATAN work in radians, so using rad2deg will screw up the answer.

[lightnb]

Originally Posted by Paul M

AFAIK, in php both TAN and ATAN work in radians, so using rad2deg will screw up the answer.

What should it be then? if $MF needs to be a decimal, and $FA is in degrees?