How do you use a calculator to approximate #arctan15#? Trigonometry Inverse Trigonometric Functions Basic Inverse Trigonometric Functions 1 Answer Tony B Aug 7, 2018 Look for the key: #tan^(-1)#. Press that then enter 15. What happens next depends on the calculator. You need to 'initiate' what you just typed in. I get: #86.1859251......# So for one along you go up #86.1859251......# Answer link Related questions What are the Basic Inverse Trigonometric Functions? How do you use inverse trig functions to find angles? How do you use inverse trigonometric functions to find the solutions of the equation that are in... How do you use inverse trig functions to solve equations? How do you evalute #sin^-1 (-sqrt(3)/2)#? How do you evalute #tan^-1 (-sqrt(3))#? How do you find the inverse of #f(x) = \frac{1}{x-5}# algebraically? How do you find the inverse of #f(x) = 5 sin^{-1}( frac{2}{x-3} )#? What is tan(arctan 10)? How do you find the #arcsin(sin((7pi)/6))#? See all questions in Basic Inverse Trigonometric Functions Impact of this question 1566 views around the world You can reuse this answer Creative Commons License