Misinterpretation of Mohr's Circle Rotation Formula?

[chetzread]

Homework Statement

for the τx'y' , i use the formula of -0.5(σx - σy)sin2θ + τxycos2θ , i found the ans is -41.3 rather than positive 41.3 , which part of my working is wrong? or I misunderstood something?

Homework Equations

The Attempt at a Solution

 

[chetzread]

here's the formula:

 

[chetzread]

after checking many times, I still couldn't find out the mistake

 

[chetzread]

anyone can help ?

 

[chetzread]

anyone have idea?
I don't know which part i gone wrong
I used the formula in page 22 in the link below:

https://web.iit.edu/sites/web/files...Academic Resource Center/pdfs/Mohr_Circle.pdf

 

[chetzread]

bump

 

[chetzread]

or it's wrong to use the transformation equation to do this question?

 

[NascentOxygen]

Unfortunately, it seems that you are not getting a response at the moment.

Have you looked at the "similar" threads listed at the foot of this page, to see whether something similar may have previously been discussed? Sometimes one can be lucky!

 

[chetzread]

Unfortunately, it seems that you are not getting a response at the moment.

Have you looked at the "similar" threads listed at the foot of this page, to see whether something similar may have previously been discussed? Sometimes one can be lucky!

Which thread?

 

[NascentOxygen]

Which thread?

You don't see links to some past threads when
you scroll way down below here [emoji652]

 

[chetzread]

You don't see links to some past threads
way down here [emoji652]

no, i don't think i can find the answer for this question in other thread,can you help?

 

[chetzread]

I have also used sin2(-θ) and cos2(-θ) instead of sin2(θ) and cos2(θ), but i still couldn't find the answer same as the author , which part of my working goes wrong
?

 

[NascentOxygen]

can you help?

The topic is one I know nothing about, I'm sorry.

 

[chetzread]

The topic is one I know nothing about, I'm sorry.

ok , anyone else can help ?

 

[chetzread]

bump