Suppose cos Q = 0.4 in the diagram below. What is QR?
Cos Q ? Q is a right angle....cos = 0
If cos R = 0.4
then cos R = adj/hyp = QR/9
.4 = QR / 9 then QR = 3.6 units
Oh wait I used the wrong diagram
.4 = 12/QR
+37146 
