Be Excellent To Each Other

OK, I have to write some code that does some calculations. Basic trig.

Formula I have been given is (Vu) = u x sinA

Where u is the launch velocity and A is the launch angle.

The example I have been given is u=200, A=30, so

Vu = 200 x sin30 = 100

When I do 200 * Math.sin(30) in Java, it gives me -0.988. When I do the same in Excel (=SIN(30)) I get same value.

Same for the next formula (Hu) + u x cosA Example given:

Hu = 200 x cos(30) = 173.2

Except 200 * Math.cos(30) = 30.85 (And same again in Excel.)

Am I missing something here? Does sinA mean something other that Sine of A? Does cosA mean something other than Cosine of A?

cos(30) is 0.867 somakes no sense at all.

Ah -- cos(30) in radians is 0.154. That's your problem. Inconsistent units.

30 is in degrees.
sin/cos in programming stuff takes radians, so you need to do..

sin( angle * (3.151592 / 180) )
(thats PI / 180 as PI radians = 180 degrees)

I concur.

WTF. Why radians? Who in the world ever uses radians?

Radiologists, DURR

Ah.... hold a sec.

Math.cos(30) isn't the Cosine of 30 degrees is it? 30 must be something else.

*Googles*

Radians! I've got to convert degrees to radians...


Edit: You lot beat me to it...

Serious people doing srs bsns.

The Police in Norn Irn?

Cheers all, award yourself some bananas.

Thanks. Glad I helped.

You helped. In that I didn't feel so alone.

Degree level stuff is full of the bastards. They're useful for trig-style algebra and whatnots.

The trig style algebra was pretty much the only part of the maths stuff I could manage in my degree. I have absolutely no idea what you'd apply to to in the real world, but it was handy to be able to be able to answer a few of the exam questions correctly.