{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# 7.3 - 7.3 Trigonometric Substitution(Dated To make the...

This preview shows pages 1–2. Sign up to view the full content.

7.3: Trigonometric Substitution (Dated: October 20, 2011) To make the trigonometric substitutions x = a sin θ , x = a tan θ , and x = a sec θ , one needs to restrict θ such that x = x ( θ ) is one-to-one. Also, these trigonometric substitutions are effective for different radical expressions in view of the specified trigonometric identities. 1. x = a sin θ is effective for the radical expression p a 2 - x 2 because 1 - sin 2 θ = cos 2 θ . One usually re- stricts θ to the intervals - π 2 < θ π 2 or - π 2 θ < π 2 . 2. x = a tan θ is effective for the radical expression p a 2 + x 2 because 1 + tan 2 θ = sec 2 θ . One usually re- stricts θ to the interval - π 2 < θ < π 2 . 3. x = a sec θ is effective for the radical expression p x 2 - a 2 because sec 2 θ - 1 = tan 2 θ . One usually re- stricts θ to the intervals 0 θ < π 2 or π θ < 3 π 2 . Example 1 [Exercise 7.3.6 in the text] Let x = sec θ , 0 θ < π 2 . Then p x 2 - 1 x = p sec 2 θ - 1 sec θ = p tan 2 θ sec θ = | tan θ | sec θ = tan θ sec θ and dx = sec θ tan θ d θ . It follows that Z p x 2 - 1 x dx = Z | tan θ | sec θ sec θ tan θ d θ = Z tan 2 θ d θ = Z (sec 2 θ - 1) d θ = tan θ - θ + C .

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern