Answer:
cosθ= [tex] \frac{ \sqrt{15} }{8} [/tex]
Step-by-step explanation:
Please see attached picture for full solution.
In the 4th quadrant, the cosine of an angle is positive.
The opposite side takes the negative sign in -⅞ since it is below the x-axis. Likewise, we reject [tex]x = - \sqrt{15} [/tex] since x lies on the right side of the y axis.