A collection of three worksheets on the following topics:

* Sum of angles in a triangle: evaluating the third angle in a triangle given the other two using the fact that their sum is 180 degrees

* Triangle inequalities: deciding whether three numbers can represent the lengths of the sides of a triangle and determining the possible lengths of the third side of a triangle given the lengths of the other two sides

* Isosceles triangles: deciding whether a given triangle is an isosceles triangle using the properties of isosceles triangles( two equal sides, two equal angles, any two of the median, bisector and height corresponding to the same side coincide). 

Detailed solutions are included.