Figure 3 shows parallelogram RSTU.Sides R U and S T are horizontal,with S T above,and
slightly to the left of side R U.Diagonal S U,which extends from vertex S at the upper left of the
parallelogram to vertex U at the lower right of the parallelogram,divides the parallelogram into
two triangles,R S U and U S T; and the angle at vertex S into 2 adjacent angles R S U and U S T.The measure of angle R S U is x degrees,and the measure of angle U S T is y degrees
图3显示平行四边形RSTU.边RU与ST平行,ST在RU上方,并且比RU稍微偏左.连接左上顶点S和右下顶点U的对角线SU,将平行四边形划分为两个三角形RSU和UST,并将角划分为角RSU和UST.角RSU为x度,角UST为y度.