{"id":5831,"date":"2021-10-03T18:34:48","date_gmt":"2021-10-03T13:04:48","guid":{"rendered":"https:\/\/mathemerize.com\/?p=5831"},"modified":"2021-11-25T23:56:00","modified_gmt":"2021-11-25T18:26:00","slug":"integration-of-secx","status":"publish","type":"post","link":"https:\/\/mathemerize.com\/integration-of-secx\/","title":{"rendered":"Integration of Secx"},"content":{"rendered":"
Here you will learn proof of integration of secx or sec x and examples based on it.<\/p>\n
Let’s begin –<\/p>\n
\nThe integration of sec x is log |sec x + tan x| + C\u00a0<\/strong>or \\(log |tan ({\\pi\\over 4} + {x\\over 2})|\\) + C<\/strong>.<\/p>\n
where C is the integration constant.<\/p>\n
i.e. \\(\\int\\) sec x = log |sec x + tan x| + C<\/p>\n
or, \\(\\int\\) sec x = \\(log |tan ({\\pi\\over 4} + {x\\over 2})|\\) + C<\/p>\n<\/blockquote>\n
Proof :<\/strong><\/p>\n
\nLet I = \\(\\int\\) sec x dx.\u00a0<\/p>\n
Multiply and divide both denominator and numerator by sec x + tan x.<\/p>\n
Then, I = \\(\\int\\) \\(sec x(sec x + tan x)\\over (sec x + tan x)\\) dx<\/p>\n
Let sec x + tan x = t. Then,<\/p>\n
d(sec x + tan x) =dt<\/p>\n
\\(\\implies\\) \\((sec x tan x + sec^2 x)\\) dx = dt<\/p>\n
\\(\\implies\\) dx = \\({dt\\over sec x (sec x + tan x)}\\)<\/p>\n
Putting sec x + tan x = t and dx = \\({dt\\over sec x (sec x + tan x)}\\), we get<\/p>\n
I = \\(\\int\\) \\(sec x (sec x + tan x)\\over t\\) \\(\\times\\) \\({dt\\over sec x (sec x + tan x)}\\)<\/p>\n
= \\(\\int\\) \\(1\\over t\\) dt = log | t | + C<\/p>\n
= log |sec x + tan x| + C<\/p>\n
Hence, I = log |sec x + tan x| + C<\/p>\n<\/blockquote>\n
Example<\/span><\/strong> : Evaluate \\(1\\over \\sqrt{1 + cos 2x}\\) dx.<\/p>\n
Solution<\/strong><\/span> : We have,<\/p>\n
I = \\(1\\over \\sqrt{1 + cos 2x}\\)<\/p>\n
By using differentiation formula, 1 + cos 2x = \\(2 cos^2 x\\)<\/p>\n
\\(\\implies\\) I = \\(1\\over \\sqrt{2cos^2 x}\\)<\/p>\n
\\(\\implies\\) I = \\(1\\over \\sqrt{2}\\) \\(1\\over cos x\\) dx<\/p>\n
= \\(1\\over \\sqrt{2}\\) \\(\\int\\) sec x dx<\/p>\n
= \\(1\\over \\sqrt{2}\\) log |sec x + tan x| + C<\/p>\n
\nRelated Questions<\/h3>\n
What is the Differentiation of sec x ?<\/a><\/p>\n
What is the Integration of Sec Inverse x and Cosec Inverse x ?<\/a><\/p>\n
What is the Differentiation of sec inverse x ?<\/a><\/p>\n\n\n