1. Given that sinx = 4/5 and cosy=-15/17, such that both x and y are in the same quadrant.Without finding x and y, determine the exact values of the following trigonometric expression. sec(x+y)
Please show all steps. I appreciate it.
since sinx is positive and cosy is negative, you are in QII
You have a 3-4-5 triangle and a 8-15-17 triangle
so,
cosx = -3/5
siny = 8/17
sec(x+y) = 1/cos(x+y) = 1/(cosx cosy - sinx siny)
= 1/((-3/5)(-15/17)-(4/5)(8/17)) = 85/13