Trigonometry
If cos(a)=1/2 and sin(b)=2/3, find sin(a+b), if
1) Both angles are acute; Answer: (sqrt(15)+2)/6
ii) a is an acute angle and pi/2 < b < pi; Answer: (2sqrt(15))/6
2. Find the exact value of the six trigonometric functions of 13pi/12.
Partial answer: cos(13pi/12)=(sqrt(6)+sqrt(2))/4
asked by
Brandi

13/12 = 5/4  1/6
sin 5pi/4 = 1/√2
cos 5pi/4 = 1/√2
sin pi/6 = 1/2
cos pi/6 = √3/2
so,
sin(13pi/12) = sin(5pi/4  pi/6) = (1/√2)(√3/2)(1/√2)(1/2) = (1√3)/√8
and so on for the othersposted by Steve
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