{"id":9384,"date":"2022-01-11T01:39:12","date_gmt":"2022-01-10T20:09:12","guid":{"rendered":"https:\/\/mathemerize.com\/?p=9384"},"modified":"2022-01-11T01:54:06","modified_gmt":"2022-01-10T20:24:06","slug":"prove-that-tan-a-tan-60-a-tan-60-a-3-tan-3a","status":"publish","type":"post","link":"https:\/\/mathemerize.com\/prove-that-tan-a-tan-60-a-tan-60-a-3-tan-3a\/","title":{"rendered":"Prove that tan A + tan (60 + A) –\u00a0 tan (60 – A) = 3 tan 3A."},"content":{"rendered":"
We have,<\/p>\n
L.H.S = tan A + tan (60 + A) – tan (60 – A)<\/p>\n
\\(\\implies\\) L.H.S = tan A + \\(\\sqrt{3} + tan A\\over 1 – \\sqrt{3} tan A\\) – \\(\\sqrt{3} – tan A\\over 1 + \\sqrt{3} tan A\\)<\/p>\n
[ By using this formula, tan (A + B) = \\(tan A + tan B\\over 1 – tan A tan B\\) above ]<\/p>\n
\\(\\implies\\) L.H.S = tan A + \\(8 tan A\\over 1 – 3 tan^2 A\\)<\/p>\n
\\(\\implies\\) L.H.S = \\(9 tan A – 3 tan^3 A\\over 1 – 3 tan^2 A\\)<\/p>\n
L.H.S = 3(\\(3 tan A – tan^3 A\\over 1 – 3 tan^2 A\\))<\/p>\n
Since \\(3 tan A – tan^3 A\\over 1 – 3 tan^2 A\\) = tan 3A<\/p>\n
\\(\\implies\\) L.H.S = 3 tan 3A = R.H.S<\/p>\n","protected":false},"excerpt":{"rendered":"
Solution : We have, L.H.S = tan A + tan (60 + A) – tan (60 – A) \\(\\implies\\) L.H.S = tan A + \\(\\sqrt{3} + tan A\\over 1 – \\sqrt{3} tan A\\) – \\(\\sqrt{3} – tan A\\over 1 + \\sqrt{3} tan A\\) [ By using this formula, tan (A + B) = \\(tan A …<\/p>\n