How does the value of differ from ?
This is an interesting question, especially because the question of units in trigonometric and inverse trigonometric functions is rarely discussed in mathematics textbooks.
If you’re interested, think this problem through on your own. Then check Problem of the Day 86 at my other site, on or after 23 April 2013, for a discussion.
QED Insight (Santo D’Agostino)

Recent Posts
 How does the value of an inverse cosine function change when the unit of its argument changes?
 Why do Airplanes Fly?
 New Online Tutoring Site: QED Infinity
 “Religious Right’s Rejection of Science is Baffling,” by David Suzuki
 The Day Niagara Falls Ran Dry
 “A Lesson in Teaching to the Test, From E.B. White,” by Anne Stone and Jeff Nichols
 “Student Learning Can Only Be Described, Not Measured,” by Rog Lucido
 A Neat Trick For Determining The Integrals Of exp(x) cos x And exp(x) sin x
 “No Student Left Untested,” by Diane Ravitch
 Confusing Use Of Numbers: BestBefore Dates
May 2015 M T W T F S S « Apr 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Education
Environment
Humour
Life Resources
Mathematics
Physics
TeX and friends
Categories
 Art (1)
 Book reviews (1)
 Books (7)
 Calculus (4)
 Calculus problems (1)
 Chess (1)
 Economics (4)
 Education (45)
 Environment (7)
 Health (1)
 Humour (14)
 Logic puzzles (1)
 Math puzzles (9)
 Mathematics (39)
 Mathematics in everyday life (1)
 Movies (3)
 Music (1)
 Nature (2)
 Neuroscience (1)
 Numeracy (2)
 People (6)
 Physics (28)
 Physics problems (3)
 Physics puzzles (4)
 Poetry (7)
 QED Infinity (1)
 QED Insight (1)
 Rants (1)
 Science research (2)
 Society (9)
 Software (1)
 Sports (1)
 Thinking puzzles (5)
 Uncategorized (3)
 What is science? (6)
 Words (9)
Archives
 April 2013 (2)
 February 2013 (1)
 April 2012 (1)
 March 2012 (2)
 February 2012 (9)
 January 2012 (3)
 December 2011 (7)
 October 2011 (5)
 September 2011 (4)
 August 2011 (2)
 July 2011 (2)
 June 2011 (7)
 May 2011 (14)
 April 2011 (15)
 March 2011 (13)
 February 2011 (29)
 January 2011 (28)
 December 2010 (1)
Meta
 Art Book reviews Books Calculus Calculus problems Economics Education Environment Humour Logic puzzles Mathematics Math puzzles Movies Music Nature Neuroscience Numeracy People Physics Physics problems Physics puzzles Poetry Rants Science research Society Sports Thinking puzzles Uncategorized What is science? Words