{"id":9378,"date":"2022-01-11T01:36:52","date_gmt":"2022-01-10T20:06:52","guid":{"rendered":"https:\/\/mathemerize.com\/?p=9378"},"modified":"2022-01-16T17:14:21","modified_gmt":"2022-01-16T11:44:21","slug":"tan-3a-formula-proof-examples","status":"publish","type":"post","link":"https:\/\/mathemerize.com\/tan-3a-formula-proof-examples\/","title":{"rendered":"Tan 3A Formula – Proof and Examples"},"content":{"rendered":"
Here you will learn what is the formula of tan 3A in terms of A with proof and examples based on it.<\/p>\n
Let’s begin –<\/p>\n
The formula of tan 3A<\/strong> is \\(3 tan A – tan^3 A\\over 1 – 3 tan^2 A\\).<\/strong><\/p><\/blockquote>\n
Proof :<\/strong><\/p>\n
We have,<\/p>\n
tan (A + B) = \\(tan A + tan B\\over 1 – tan A tan B\\)<\/p>\n
Replacing B by 2A,<\/p>\n
\\(\\implies\\) tan 3A = \\(tan A + tan 2A\\over 1 – tan A tan 2A\\)<\/p>\n
Since, tan 2A = \\(2 tan A\\over tan^2 A\\)<\/p>\n
\\(\\implies\\) tan 3A = \\(tan A + {2 tan A\\over tan^2 A}\\over 1 – tan A \\times {2 tan A\\over tan^2 A}\\)<\/p>\n
\\(\\implies\\) tan 3A = \\(tan A (1 – tan^2 A) + 2 tan A\\over 1 – tan^2 A – 2 tan^2 A\\) = \\(3 tan A – tan^3 A\\over 1 – 3 tan^2 A\\)<\/p>\n
Hence, tan 3A = \\(3 tan A – tan^3 A\\over 1 – 3 tan^2 A\\)<\/p>\n
We can also write above relation of angle A in terms of angle A\/3, just replace A by A\/3, we get<\/p>\n
tan A = \\(3 tan ({A\\over 3}) – tan^3 ({A\\over 3})\\over 1 – 3 tan^2 ({A\\over 3})\\)<\/p><\/blockquote>\n
Example<\/strong><\/span> : Prove that tan A + tan (60 + A) – tan (60 – A) = 3 tan 3A.<\/p>\n
Solution<\/span><\/strong> : 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":"
Here you will learn what is the formula of tan 3A in terms of A with proof and examples based on it. Let’s begin – Tan 3A Formula The formula of tan 3A is \\(3 tan A – tan^3 A\\over 1 – 3 tan^2 A\\). Proof : We have, tan (A + B) = \\(tan …<\/p>\n