(A)2√2
(B)6√2
(C)4√2
(D)5√2
find the value of \sqrt{3}(sec55+cosec55) + sec55 - cosec55
surprisingly ,the answer consists of only 1 term(irrational)
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5 Answers
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·2009-03-31 12:01:39
(1/sin55.cos55).(√3sin55 - cos55 + √3cos55 + sin55)
= (2/sin55.cos55).[(cos30.sin55 - sin30.cos55) + (cos30.cos55 + sin30.sin55)]
= (4/sin110).[(cos25 + sin25]
= (4√2/cos20).[sin45.cos25+cos45.sin25]
= (4√2/cos20).[sin70]
= (4√2/cos20).cos20
= 4√2.
correct me if i am wrong !