1.22 Generate plots for each of the following functions over the time span from −4 s to +4 s. (a) x1(t) = 5r(t + 2) − 5r(t) (b) x2(t) = 5r(t + 2) − 5r(t) − 10u(t) ∗(c) x3(t) = 10 − 5r(t + 2) + 5r(t) (d) x4(t) = 10rect?t + 1 2 ? − 10rect?t − 3 2 ? (e) x5(t) = 5rect?t − 1 2 ? − 5rect?t − 3 2 ?

Given: ae ≅ ce ; de ≅ be prove: abcd is a parallelogram. we have that ab || dc. by a similar argument used to prove that △aeb ≅ △ced, we can show that △ ≅ △ceb by. so, ∠cad ≅ ∠ by cpctc. therefore, ad || bc by the converse of the theorem. since both pair of opposite sides are parallel, quadrilateral abcd is a parallelogram.