Measures of parts

Type of Triangle

Explanation

(i) 3 sides of equal lengths

(e) Equilateral

Equilateral triangle has all three sides equal. 

(ii) 2 sides of equal lengths

(g) Isosceles

Iscoles triangle has any two sides equal. 

(iii) All sides are of different lengths

(a) Scalene

Scalene triangle has all the three sides different.

(iv) 3 acute angles

(f) Acute-angled

When all the three angles of a triangle are less than 45^o, then it is an acute-angled triangle. 

(v) 1 right angle

(d) Right-angled

When any one angle of a triangle is 90^o, then it is a right-angled triangle. 

(vi) 1 obtuse angle

(c) Obtuse-angled

When any one angle of a triangle is greater than 90^o but less than 180^o, then it is an obtuse-angled triangle. 

(vii) 1 right angle with sides of equal lengths

(b) Isosceles right-angled

When any two sides of a triangle are equal and one angle of the triangle is 90^o, then it is an Isosceles-right-angled triangle.