Quandaries
and Queries
Name: Kyle
Student, Secondary Question
I would like to know how to evaluate the problem of: Arccos 5/13.
Thank you.
Hi Kyle,
I expect that what you want is some trig function of arccos(5/13), like maybe
tan(arccos(5/13))
I would start by drawing a triangle.
In this diagram the angle ABC has a cosine of 5/13. In other words
arccos(5/13) = angle ABC
By Pythagoras' theorem
52 + |CB|2 = 132
that is
|CA|2 = 132 - 52 = 169 - 25 = 144 so
|CA| = 12
Now you can read the trig functions of angle ABC from the diagram, for example
tan(arccos(5/13)) = 12/5
I hope this helps,
Penny