# Trigonemetry Graphs

• May 9th 2007, 06:06 AM
janvdl
Trigonemetry Graphs
I got a Sin and Tan Graph.

The sin graph's formula: y = a sin x
The tan graph's formula: y = tan 1/a x

These two graphs cross at 120 degrees.

So that means:
a sin 120 = tan 1/a 120

But how can i find the value of a? :confused: Somewhere im missing something.
• May 9th 2007, 09:31 AM
CaptainBlack
Quote:

Originally Posted by janvdl
I got a Sin and Tan Graph.

The sin graph's formula: y = a sin x
The tan graph's formula: y = tan 1/a x

These two graphs cross at 120 degrees.

So that means:
a sin 120 = tan 1/a 120

But how can i find the value of a? :confused: Somewhere im missing something.

a=+/-2

How did I find these solutions - educated guess and check

OK really - use a numerical method which suggested that 2 might be a root,
checking proved that this was indeed the case, then symettry suggest -2
is also a root. Then there is some very nasty behaviour for small a which
I will have to think about.

RonL
• May 9th 2007, 09:33 AM
janvdl
Quote:

Originally Posted by CaptainBlack
a=+/-2 +n*pi for n=0, +/-1, ...

RonL

Sorry, i saw only now you said you guessed.

So theres no way of calculating this??? :(
• May 9th 2007, 09:41 AM
janvdl
Why is "a" so very nasty? I mean, for goodness' sake i'm only in matric, not varsity. :)
• May 9th 2007, 09:48 AM
r_maths
Off topic sorry.

Is matric/varsity a High School/College/Uni ?
• May 9th 2007, 09:49 AM
janvdl
Matric is the highest grade of high school.
Varsity means university.

:)
• May 9th 2007, 10:09 AM
CaptainBlack
Quote:

Originally Posted by janvdl
Why is "a" so very nasty? I mean, for goodness' sake i'm only in matric, not varsity. :)

If you have something suitable try plotting

y=x sin(120) - tan(120/x)

for x=0.00001 to 1.

RonL