My Question

Im explaining question 12 from the June 2009 Student Booklet Part 2.



Question
12. On the unit circle shown, the coordinates of P are (a, b).
The value of sec(theta) is:
a) a
b) b
c) 1/a
d) 1/b

Solution
The ratio for secant(theta) is hypotenuse/adjacent which would be 1/x on a unit circle.
The x value for the point is a so by substituting a in for x you get the solution: c) 1/a