Question 519116
Find the exact value of tan 15 by using the composite argument property for tan(A + B) and clever choices for A and B. Write the answer in simple radical form. 
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Trig identity: tan(s-t)=(tan s-tan t)/(1-tan s tan t)
tan15=tan(45-30)=(tan45-tan30)/(1+tan45*tan30)
tan45=1
tan30=√3/3
tan15=(1-√3/3)/(1+1*√3/3)
tan15º=(1-√3/3)/(1+√3/3)