How can I simplify this expression without using a calculator?

[zorro]

Homework Statement

I got this expression while solving a problem.

sin(theta)=[√3+1-√(4-2√3)]/4
Using calculator I got RHS=0.5
How do we simplify it without using a calc?

Homework Equations

The Attempt at a Solution

 

[ehild]

Try to write 4-2√3 as the square of (√3-a) . What is a?

ehild

 

[HallsofIvy]

ehild, did you intend that to be $\sqrt{(3- a)}$ or $(\sqrt{3})- a$?

 

[ehild]

Naturally, √3 +a = 1.7320508.. +a. You have to perform a higher operation first, and square root is of higher order than addition or subtraction. So is multiplication to addition. 2*3+4 =10 and it is not the same as 2*(3+4)=14. Or 6/2+3=6, and not 6/(2+3)=1.2. √9+16=19 and it is not √(9+16)=5. The square of (√3-1) is (√3-1)^2 = 4-2√3 and not √3-1^2=√3-1. Or it is on the other way at other parts of the world?

ehild

 

[Mentallic]

Naturally, √3 +a = 1.7320508.. +a. You have to perform a higher operation first, and square root is of higher order than addition or subtraction. So is multiplication to addition. 2*3+4 =10 and it is not the same as 2*(3+4)=14. Or 6/2+3=6, and not 6/(2+3)=1.2. √9+16=19 and it is not √(9+16)=5. The square of (√3-1) is (√3-1)^2 = 4-2√3 and not √3-1^2=√3-1. Or it is on the other way at other parts of the world?

ehild

Yes?

Abdul Quadeer, $$a+b=\sqrt{(a+b)^2}$$, see if you can work some magic with this idea.

 

[zorro]

Thanks, I got the answer.
Mentallic- there is a slight error in your idea.
LHS =|a+b|

 

[Mentallic]

Haha yep I didn't want to complicate things by saying in the case that a+b>0 or anything like that. You know, the KISS principle. But I'm glad you were able to spot my simplification (in other words, the error, but I'm not willing to admit it )

 

[zorro]