Log In Start studying!

Select your language

Suggested languages for you:
Answers without the blur. Sign up and see all textbooks for free! Illustration

Q33E

Expert-verified
Essential Calculus: Early Transcendentals
Found in: Page 216
Essential Calculus: Early Transcendentals

Essential Calculus: Early Transcendentals

Book edition 2nd
Author(s) James Stewart
Pages 830 pages
ISBN 9781133112280

Answers without the blur.

Just sign up for free and you're in.

Illustration

Short Answer

Prove the identity

\(arcsin\frac{{x - 1}}{{x + 1}} = 2arctan\sqrt x - \frac{\pi }{2}\).

The identity \(\arcsin \frac{{x - 1}}{{x + 1}} = 2\arctan \sqrt x - \frac{\pi }{2}\) is proved.

See the step by step solution

Step by Step Solution

 Step 1: Given data

The functions is \(\arcsin \frac{{x - 1}}{{x + 1}} = 2\arctan \sqrt x - \frac{\pi }{2}\).

Step 2: Use theorem

"If \({f^\prime }(x) = 0\) for all \(x\) in an interval \((a,\;b)\), then \(f\) is constant on \((a,\;b)\)."

Step 3: Find the value for \(x + 1\)

Rewrite the given equation as follows:

\({\sin ^{ - 1}}\frac{{x - 1}}{{x + 1}} = 2{\tan ^{ - 1}}\sqrt x - \frac{\pi }{2}\).

Let, \({\sin ^{ - 1}}\frac{{x - 1}}{{x + 1}} = \alpha \) and solve for \(\alpha = 2{\tan ^{ - 1}}\sqrt x - \frac{\pi }{2}\) as follows:

\(\begin{aligned}{c}{\sin ^{ - 1}}\frac{{x - 1}}{{x + 1}} &= \alpha \\\frac{{x - 1}}{{x + 1}} &= \sin \alpha \\\frac{{(x - 1) + 2 - 2}}{{x + 1}} &= \sin \alpha \\\frac{{x - 1 + 2 - 2}}{{x + 1}} &= \sin \alpha \end{aligned}\)

Simplify \(\frac{{x - 1 + 2 - 2}}{{x + 1}} = \sin \alpha \) as follows:

\(\begin{aligned}{c}\frac{{(x + 1) - 2}}{{x + 1}} &= \sin \alpha \\1 - \frac{2}{{x + 1}} &= \sin \alpha \\1 - \sin \alpha &= \frac{2}{{x + 1}}\\x + 1 &= \frac{2}{{1 - \sin \alpha }}\end{aligned}\)

Step 4: Solve for \({\tan ^{ - 1}}\sqrt x \)

Simplify the above equation and obtain the value of \({\tan ^{ - 1}}\sqrt x \) as follows:

\(\begin{aligned}{c}x &= \frac{2}{{1 - \sin \alpha }} - 1x\\ &= \frac{{2 - (1 - \sin \alpha )}}{{1 - \sin \alpha }}x\\ &= \frac{{1 + \sin \alpha }}{{1 - \sin \alpha }}x\\ &= \frac{{1 - \cos \left( {\frac{\pi }{2} + \alpha } \right)}}{{1 + \cos \left( {\frac{\pi }{2} + \alpha } \right)}}\end{aligned}\)

Simplify \(x = \frac{{1 - \cos \left( {\frac{\pi }{2} + \alpha } \right)}}{{1 + \cos \left( {\frac{\pi }{2} + \alpha } \right)}}\) as follows:

Step 5: Solve for \(2{\tan ^{ - 1}}\sqrt x  - \frac{\pi }{2}\)

Simplify the above equation and obtain the value of \(2{\tan ^{ - 1}}\sqrt x - \frac{\pi }{2}\) as follows:

Hence, the given identity is proved.

Recommended explanations on Math Textbooks

94% of StudySmarter users get better grades.

Sign up for free
94% of StudySmarter users get better grades.