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FinalFantasy

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taco man said:
Hi i was wonderin if sum1 could do this question for me:
Find the exact value of sin(13 pi/12)

thx
sin(13pi\12)=sin 195=-sin 15=-sin(60-45)=-(sin60cos45-cos60sin45)
then u can do it
 

taco man

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sry to bother every1 again but heres a another question:
Prove: sin(A+B)/cos(A-B)=tanA+tanB/1+(tanA)(tanB)

thx
 

FinalFantasy

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taco man said:
sry to bother every1 again but heres a another question:
Prove: sin(A+B)/cos(A-B)=tanA+tanB/1+(tanA)(tanB)

thx
LHS=sin(A+B)/cos(A-B)=(sinAcosB+cosAsinB)\(cosAcosB+sinAsinB)
RHS=tanA+tanB/1+(tanA)(tanB)
=[(sinA\cosA)+(sinB\cosB)]\[1+(sinA\cosA)(sinB\cosB)]
=(sinAcosB+cosAsinB)\(cosAcosB) \ (cosAcosB+sinAsinB)\cosAcosB
=sinAcosB+cosAsinB\cosAcosB+sinAsinB
=LHS
 

taco man

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Hey just wonderin why is the graph of -tan^(-1) (1-x)----(1-x is not a power) is shifted left , shouldnt it be it shifted right 1 units left since -x+1?
 
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mojako

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taco man said:
Hey just wonderin why is the graph of -tan^(-1) (1-x)----(1-x is not a power) is shifted left , shouldnt it be it shifted right 1 units left since -x+1?
tan^(-1) (x+1) is tan^(-1) (x) shifted left by 1 unit.
-tan^(-1) (1-x) is -tan^(-1) (-x) shifted left by 1 unit.
 

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