Name each of the following triangles in two different ways: (you may judge the nature of the angle by observation).

(a)

(b)

(c)

(d)

(e)

(f)

(a) Acute-angled and isosceles triangle

As in this figure we can see all angles are less than 90° and it has two equal sides and these are the property of acute angle and isosceles triangle.

(b) Right-angled scalene triangle

As the triangle has one right angle and three unequal sides and these are the property of right-angled and scalene triangle.

(c) Obtuse-angled and isosceles triangle

As we can see one angle is greater than 90° and it has two equal sides and these are the property of obtuse angle and isosceles triangle.

(d) Right-angled and isosceles triangle

As it has one angle of 90° and two equal sides and these are the property of right-angled and isosceles triangle.

(e) Acute-angled and equilateral triangle

As in the figure we can see all angles are less than 90° and it has all equal sides and these are the property of acute angle and equilateral triangle.

(f) Obtuse-angled and scalene triangle

As we can see one angle is greater than 90° and three unequal sides and according to the property of triangles only obtuse-angled and scalene triangle has these property.