22. In trapezoid RSTV, RV || ST, mZSRV = 90, and M and N are midpoints of the nonparallel sides. a) What type of triangle is ARMN? b) If ST 13, RV = 17, and RS = = 16, how long is RN? c) What type of triangle is ARVN? R M S [HINT: Use lengths of sides found in part (b).] T PA