Name the types of following triangles: (a) Triangle with lengths of sides 7 cm, 8 cm and 9 cm. (b) ∆ABC with AB = 8.7 cm, AC = 7 cm and BC = 6 cm. (c) ∆PQR such that PQ = QR = PR = 5 cm. (d) ∆DEF with m triangle D = 90° (e) ∆XYZ with m triangle Y = 90° and XY = YZ (f) ∆LMN with m triangle L = 30° , m triangle M = 70° and m triangle N = 80° .