Soil mechanics, earth pressure, trig/algerbra query

[Nathanscott90]

Hi
Please can someone help me with the derrivation of
1-sin theta / 1+sin theta

from (sigma1 + sigma3) sin theta = (sigma 1 - sigma 3)

Thanks

Should add, sigma 1 / sigma 3 = 1 - sin theta / 1 + sin theta

 

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[Cubist]

Hi
Please can someone help me with the derrivation of
1-sin theta / 1+sin theta

from (sigma1 + sigma3) sin theta = (sigma 1 - sigma 3)

Thanks

Please use brackets to make your expressions PEMDAS friendly . I assume that you are given...

(σ₁ + σ₃) sin(θ) = σ₁ - σ₃

and you wish to find

(1 - sin(θ)) / (1 + sin(θ)) = something in terms of σ₁ and σ₃

Is this correct? Please show us what you have tried and where you got stuck.

--

Should add, sigma 1 / sigma 3 = 1 - sin theta / 1 + sin theta

I'm pretty sure this is wrong, if your first post is correct - please check

 

[Deleted member 4993]

Hi
Please can someone help me with the derrivation of
(1-sin theta) / (1+sin theta)

from (sigma1 + sigma3) sin theta = (sigma 1 - sigma 3)

Thanks

Should add, sigma 1 / sigma 3 = (1 - sin theta) / ( 1 + sin theta)

Please add "parentheses" ( ) to indicate order of operation.

Please define σ₁ and σ₃

Please define reference directions for Θ - i.e. Θ is the angle between which two lines/directions?