Simple maths question

[unclebob123]

If you know the length of 'x' and the angle of 'y', how do you work out the length of 'z'? Both of the marked angles are the same.

Cheers

 

[Haircut]

Guess?

Without more information about how x, y and z are related you really can't tell.
Presumably this is in a triangle?

EDIT: I see there is a picture now. You need to look up the cosine rule

 

[Sinque]

http://www.ucl.ac.uk/mathematics/geomath/trignb/trig12.html

 

[unclebob123]

There should be a picture there now. I linked it wrong at first so didn't show up.

Oh and to add both the marked angles are the same.

 

[clv101]

Sure you can work it out... Just remember:
a^2 = b^2 + c^2 - 2bc cosA and a/sinA = b/sinB = c/sinC

 

[GeForce]

If 'y' is in degrees:

z = x.sin(y) / sin(180-2y)

Edit: for clarity

 

[J.B]

Maths home work not going too well?

 

[Viper²]

Isn't Trigonometry taught at school?

 

[gareth.e]

With big trig thats what my teacher said

 

[mattheman]

If you know the length of 'x' and the angle of 'y', how do you work out the length of 'z'? Both of the marked angles are the same.

Cheers

simple draw it.

 

[clv101]

With the angles the same you can just use Z = 0.5X/cosY.

 

[unclebob123]

ok because im an idiot, can I subsitute some of those letters in the pic for numbers and you show the working for me.

So y = 30 degrees and x = 10cm

cheers

 

[unclebob123]

ok thanks everyone that makes more sence now.

Yeah I was taught it, but this was a long time ago ( well only about 4 years) and I haven't needed it since.

 

[Sinque]

simple draw it.

You really should get banned for trolling...

 

[Manics]

The answer is C.

 

[GeForce]

The solution I posted is sine rule.

clv101's is actually simpler and works by splitting the triangle into two right-angled ones.

z = 0.5x / cox Y = (10/2) / cos(30) = 5/[sqrt(3) / 2] =~ 5.77

z = x.sin(y) / sin(180-2y)
z = (10.sin 30) / sin (180 - 2*30) = 10sin30 / sin120 = 5/[sqrt(3) / 2] =~ 5.77

 

[mattheman]

You really should get banned for trolling...

SO YOUR TELLING ME the you have the base length and the angle, you cannot draw it? as the angle on the right matches the angle on the left, draw a line on each side till they cross measure line.

 

[Sinque]

SO YOUR TELLING ME the you have the base length and the angle, you cannot draw it? as the angle on the right matches the angle on the left, draw a line on each side till they cross measure line.

Hahahahahah, measure the line - quality. Have you even gone through secondary education?

 

[clv101]

Drawing it a way of working it out. The OP only said work out, didn't specify calculate.

 

[unclebob123]

It is the work out the convergence points of two cameras for shooting stereoscopic, where x is the camera separation and y is the convergance angle of the cameras. So drawing it would not a be a practicle solution for on set.

So let me see if I have this right.

X= 10cm
y= 80 degrees

therefore z=401