9 AB is parallel to plane m and perpendicular to plane r. CD lies in r. Which of the following must be true? arim br m 6 CD L m d AB || CD e AB and CD are skew.

Suppose the x- and y-axes are routed through an acute angle to produce the new X- and Y-axes. A point P P in the plane can be described by its xy-coordinates (x,y) or its XY coordinates. These coordinates are related by the following formulas. x= X= y= Y=

In the figure, we see that mRS-=mVT-=0. Find the equation that relates r,s,andt if it is known that RSTV is a parallelogram. _