Find exact values of trigonometric equation without finding the angles

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PelajarBaik

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I am confused on how to do this without finding the angle first, please help.

My attempt :
question1.png
 
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PelajarBaik said:
View attachment 30906
I am confused on how to do this without finding the angle first, please help.
Click to expand...
If I were to do this problem, I would first calculate sinA using

sin2(A) + cos2(A) =1 and continue....

Please show us what you have tried and exactly where you are stuck.

Please follow the rules of posting in this forum, as enunciated at:


Please share your work/thoughts about this problem.
 
Subhotosh Khan said:
If I were to do this problem, I would first calculate sinA using

sin2(A) + cos2(A) =1 and continue....

Please show us what you have tried and exactly where you are stuck.

Please follow the rules of posting in this forum, as enunciated at:


Please share your work/thoughts about this problem.
Click to expand...
Im stuck at the without finding the angle part
 

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PelajarBaik said:
Im stuck at the without finding the angle part
Click to expand...

Did you calculate the value of sin(A) using the equation suggested in response #3?

You do not need to know the value of 'A' to do that.
 
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Hints for [imath]\sin(2B)[/imath],
[math]1+\tan^2(B)=\sec^2(B)=\frac{1}{\cos^2(B)}\\ \tan(B)=\frac{\sin(B)}{\cos(B)}[/math]
 
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A and B are in the same quadrant. cos A is negative AND tan B is positive. What quadrant must A and B be in?

Have you seen this before?
1643340907183.png
 
Note that sin B is negative. I think you have substituted a positive value. (Bit hard to read your photo)
 
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