Well,
Trig enables you to find an unknown in a triangle, the length of one side or an angle for example.
THE FOLLOWING ONLY WORKS WITH RIGHT-ANGLED TRIANGLES
Imagine a right angled triangle:
/|
/ |
h / |
/ | o
/ |
/*____|
a
We have an angle, *, and then we name the sides in relation to the angle. h, is the hypot. and is always the longer side. o, is the opposite side of the angle. a is adjacent to the angle.
We then have various equations we can use to calculate one of the unknowns if we know two more bits of information.
Sin* = o / h
Cos* = a / h
Tan* = o / a
What this means is that is we can work out some values...
we want to work out the angle and we know that a=3 and h=6,
what we can then do is use Cos, as we know a & h, so:
Cos* = a / h (reinstating the formula)
Cos* = 3 / 6
in order for us to find the value of the angle we need to do inverse Cos,
imagine the inverse like this
Cos: decimal value in >>> Cos function >>> angle out
Inverse Cos: angle in >>> InvCos function >>> decimal value out
so,
InvCos (3/6) = *
* = 60
Simple huh? it looks confusing but once you get used to it its easy.
So we'll now do a different question, finding a side.
Information given h=2, *=45
Sin* = o / h
Sin45 = o / 2
.:. (therefore)
2 x Sin45 = o
o = sqrt(2) = 0.7071
and the same principle follows for Sin,Cos and Tan.
It does get slightly more complicated when you don't have a right angled triangle but for now, youll be ok.
If you need more help I've got MSN so,
regards,
rich
