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

## Answer: a) scalene triangle b) scalene triangle c) equilateral triangle d) right-angled triangle e) isosceles right-angled triangle f) acute-scalene triangle

Let's solve this step by step.

**Explanation: **

(a) Triangle with lengths of sides 7 cm, 8 cm, and 9cm will have all its sides of different lengths.

Hence, it will be a scalene triangle.

(b) ABC with AB = 8.7 cm, AC = 7 cm and BC = 6cm will have all its sides of different lengths.

Hence, it will be a scalene triangle.

(c) PQR such that PQ = QR = PR = 5cm will have all its sides of equal lengths.

Hence, it will be an equilateral triangle.

(d) DEF with D = 90 degrees will have one right angle inside the triangle.

Hence, it will be a right-angled triangle.

(e) XYZ with Y = 90 and XY = YZ will have two sides of equal length, and one right angle inside the triangle.

Hence, it will be an isosceles right-angled triangle.

(f) LMN with L = 30, M = 70, and N = 80 will have all angles different, hence making all the sides different.

Hence, it will be an acute-scalene triangle.