Question

Tan5+tan15+tan25+.....+tan355=

Answer 1

"tan 355 = tan (360 – 5) = -tan 5, tan 345 = tan ( 360 – 15 ) = -tan 15, tan 335 = tan (360 – 25 ) = -tan 25, tan 325 = tan ( 360 – 35 ) = -tan 35 and so on hence all the tan values will get cancel on being added.

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