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Question
If `"sec" theta = "x" + 1/(4 "x"), "x" in "R, x" ne 0,`then the value of `"sec" theta + "tan" theta` is ____________.
Options
only 2x
only `1/(2"x")`
2x or `1/(2 "x")`
None of these
Solution
If `"sec" theta = "x" + 1/(4 "x"), "x" in "R, x" ne 0,`then the value of `"sec" theta + "tan" theta` is `underline(2"x or" 1/(2 "x"))`.
Explanation:
`"sec" theta = "x" + 1/(4"x"), "x" in "R", "x" ne 0,`
`"sec" theta = "x" + 1/ (4"x")`
`=> "tan" theta = sqrt ("sec"^2 theta - 1) = sqrt (("x" + 1/4"x")^2 - 1)`
`=> "tan" theta = sqrt ("x"^2 + 1/(4 "x")^2 + 1/2 - 1) = sqrt (("x" + 1/(4 "x"))^2`
`"tan" theta = ("x" - 1/(4"x"))`
`=> "tan" theta = "x" - 1/(4"x"), "x" in "R", "x" ne 0, =>`
`"sec" theta + "tan" theta = "x" + 1/(4"x") + "x" - 1/(4 "x") = 2 "x"`
When we will take the negative value with tan we will get an answer as 1/2x.