InterviewSolution
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InterviewSolution
| 1. |
\tan 72 ^ { \circ } = \tan 18 ^ { \circ } + \tan 54 ^ { \circ } |
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Answer» tan54 = tan(72-18) = tan54 =( tan72-tan18)/1+tan72.tan18 = tan54 = ( tan72-tan18)/1+tan(90-18).tan18 = tan54 =( tan72-tan18)/1+cot18.tan18 = tan54 =( tan72-tan18)/2 = tan72-tan18 = 2tan54 =(tan72 = tan18+2tan54) tanq |
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