Answer:
b. cos 46
Step-by-step explanation:
There are three angles to choose from since there are three angles in a triangle. Of these, the 90° angle can't be used (90° angles don't work with trigonometric ratios), and neither can the 44° (we're told to use a different one from this), so we're left with the unmarked angle on the bottom right. Since the angles in a triangle add to 180, and the other two angles total 134 (90+44=134), we can say this angle is 46°.
Since cos46 is our only option that involves this angle (and since cos46=x/9), this is the option which could be used to find x.
