We will define each type of triangles.
Isosceles triangle is a triangle with 2 congruent sides and 2 congruent angles.
Equilateral triangle is a triangle with 3 congruent sides and 3 congruent angles.
Acute triangle is a triangle with acute angles or angles less than 90 degrees.
Obtuse triangle is a triangle with one of the angles greater than 90 degrees.
Right triangle is a triangle with one of the angles measures exactly 90 degrees.
Scalene Triangle is a triangle with 3 different sides.
A. The sides are 6 cm, 10cm and 12 cm. Since the sides are all different, this is scalene triangle.
B. The triangle has 2 congruent sides, therefore this is an isosceles triangle.
C. The triangle has 3 congruent angles, therefore this is an equilateral triangle.
D. The triangle has angles that are less than 90 degrees, therefore this is an acute triangle.
E. One of the angles in the triangle measures 150 degrees which is greater than 90 degrees, therefore this is an obtuse triangle.
F. The triangle has an angle that measures 90 degrees, therefore this is a right triangle.