What's the question exactly?
According to the text the answer should come up to 2.3154725 in radian mode.
The text states: "We take the inverse tangent of the reciprocal to find the inverse cotangent".
I therefore punch in:
tan-1(1/-0.92170128)
like the examples show me but I get:
-0.826120119
OK I just fugured it out:
In degree mode I punched in:
tan-1(1/-0.92170128)
= -47.33319621
-47.33319621 + 180 (which is ∏ radians)
= 132.6668038
132.6668038/180
= 0.737037799
0.737037799 x ∏
= 2.31572534
but I can't fugure out how to get the answer strait into radians?