How do you do this question? (2021 CSSA Ext1 Trials Q13c) (1 Viewer)

[OreoMcFlurry]

Hey guys, can someone please do this question and provide a solution to this question?
(please provide working)

 

[Life'sHard]

What's the thing called when you let it be Rsin(x-alpha) then expand and equate.

 

[OreoMcFlurry]

Auxiliary Angle method I think. I did do that, here's my working (I apologise for the messy work lol):



I got 3/4 marks (which isn't bad), so I lost one mark as there's supposed to be two solutions instead of one.

 

[Life'sHard]

Auxiliary Angle method I think. I did do that, here's my working (I apologise for the messy work lol):

View attachment 32021

I got 3/4 marks (which isn't bad), so I lost one mark as there's supposed to be two solutions instead of one.

It's weird that they took out general solutions in the syllabus. X=pi/6 + 0.927 + 2kpi and X=-pi/6 + pi + 0.927 + 2kpi

 

[CM_Tutor]

The other solution is , which is @Life'sHard's second solution with to get the solution in the required domain .

 

[ExtremelyBoredUser]

Edit:

 

[CM_Tutor]

View attachment 32022

Your second solution is not in the domain .

The domain over which you need to solve for is to get the second solution as