cot15°+1/cot15°-1=?

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cot15°+1/cot15°-1=?cot15°+1/cot15°-1=?cot15°+1/cot15°-1=?(cot15°+1)/(cot15°-1)=(cos15°/sin15+1)/(cos

cot15°+1/cot15°-1=?
cot15°+1/cot15°-1=?

cot15°+1/cot15°-1=?
(cot15°+1)/(cot15°-1)
=(cos15°/sin15+1)/(cos15°/sin15-1)
=(cos15+sin15)/(cos15-sin15)
=(cos15+sin15)(cos15+sin15)/[(cos15-sin15)(cos15+sin15)]
=(cos^2 15+sin^2 15+2cos15sin15)/(cos^2 15-sin^2 15)
=(1+sin30)/cos30
=(1+1/2)/(√3/2)
=√3