Thread: confusion with simple trig problem

For each of the following functions, sketch the graph of y=f^-1(x)
f(x)=sinx°, x ϵ R and -90≈x≈90
f(x)=cosx°, x ϵ R and 0≈x≈180
f(x)=tanx°, x ϵ R and -90<x<90

To be honest I have no frigging idea what to make of the domains of the sine and cosine functions, are they typos? “x approximately equal to plus or minus 90”, what the heck is that for a domain? On the other hand the domain of the tangent function is perfectly normal, and what you would expect for the first two.
Are these just a typo from my textbook?

Originally Posted by furor celtica

For each of the following functions, sketch the graph of y=f^-1(x)
f(x)=sinx°, x ϵ R and -90≈x≈90
f(x)=cosx°, x ϵ R and 0≈x≈180
f(x)=tanx°, x ϵ R and -90<x<90

To be honest I have no frigging idea what to make of the domains of the sine and cosine functions, are they typos? “x approximately equal to plus or minus 90”, what the heck is that for a domain? On the other hand the domain of the tangent function is perfectly normal, and what you would expect for the first two.
Are these just a typo from my textbook?

They must be typos. For sin xº it shoulf be –90 ≤ x ≤ 90, and for cos xº it should be 0 ≤ x ≤ 180. Probably some typesetting program rendered the "less than or equal" symbols as "approximately equal".