Name the types of following triangles: (а) 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∠D = 90° (e) ∆XYZ with m∠Y = 90° and XY = YZ. (f) ∆LMN with m∠L = 30° m∠M = 70° and m∠N = 80°.

(a) Lengths of the sides of a triangle are given as: 7 cm, 8 cm and 9 cm. Since, all sides of the given triangle are different. Hence, it is a Scalene triangle. (b) Given that: AB = 8.7 cm, AC = 7 cm and BC = 6 cm Here AB ≠ AC ≠ BC Hence, ∆ABC is Scalene triangle. (c) Given that: PQ = QR = PR = 5 cm Since all sides are equal. Hence, it is an equilateral triangle. (d) Given that: In ∆DEF, m∠D = 90° Hence it is a right angled triangle. (e) Given that: In ∆XYZ, m∠Y = 90° and XY = YZ Hence it is a right angled triangle. (f) Given that: ∆LMN, m∠L = 30°, m ∠M = 70° and m∠N = 80°. Hence it is an acute angled triangle.