sin(a+b) identity question

martha96v

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May 3, 2016
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Hi, I am new to the forum so I'm not sure if I'm posting in right section but I'm desperate to get an answr as my exam is on following Monday and I'm stuck with this one. Sorry in advance!
Here it is:

In the diagram below QR=RS=1
Use the expansion for sin(a+b) to show that sqrt3 sinx + cos x= 4/sqrt7
attachment.php


This is what I managed to work out and would be really thankful if someone could tell me what to do from this point to get to the answer.
Thank you loads,
Marta
 

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Hi, I am new to the forum so I'm not sure if I'm posting in right section but I'm desperate to get an answr as my exam is on following Monday and I'm stuck with this one. Sorry in advance!
Here it is:

In the diagram below QR=RS=1
Use the expansion for sin(a+b) to show that sqrt3 sinx + cos x= 4/sqrt7
attachment.php


This is what I managed to work out and would be really thankful if someone could tell me what to do from this point to get to the answer.
Thank you loads,
Marta
Use the triangle (the right triangle!) with all the known sides to compute sin (30+x). The results should easily follow from there. You must try harder!
 
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